[#3605] Specialize HTTP fuzzers into v4 and v6

[#3605] Razvan's fix for ASAN warnings in fuzzing

[#3605] Integrate a new fuzzing solution in Kea

The solution is based on clusterfuzzlite, libfuzzer, and oss-fuzz
technologies.

- Add the .clusterfuzzlite directory.
- Add the fuzz CI stage and fuzzing CI jobs.
- Add the fuzzing targets in the fuzz directory.
- Document fuzzing in doxygen.

[#3605] Remove extra semis

[#3605] Prepare existing code for fuzzing

- Separate ENABLE_AFL into ENABLE_FUZZING and HAVE_AFL.
- Add the --disable-unicode flag required in the oss-fuzz container.
- Add checking of support for C++17.
- Make Kea compile with afl++.
- Rotate ports in `getServerPort()` functions under an env var.
- Fix some destruction issues that would result in crashes when fuzzing.
- Add some checks in the UnixControlClient that prevent some crashes when fuzzing.
- Add `isc::util::isSocket()` function.
- Change `isc::util::file::Path` to not append a trailing slash to allow
  chained calls of `parentPath()`.
- Add `isc::util::file::TemporaryDirectory` useful when fuzzing.

[#3630] forge db init fix

[#3582] Tab fix in changelog

[#3582] ChangeLog added

[#3582] Extended option-data toElement

[#3619] destroy maangers before hook unload

[#3351] use execve to silence valgrind on child exit

[#3351] fixed memory leaks

[#3351] Fixed leak in signal test

[#3583] Added UTs

/src/bin/dhcp4/tests/classify_unittest.cc
    TEST_F(ClassifyTest, classTaggingAndAlwaysSend)
    TEST_F(ClassifyTest, classTaggingAndNeverSend)

/src/bin/dhcp6/tests/classify_unittest.cc
    TEST_F(ClassifyTest, classTaggingAndAlwaysSend)
    TEST_F(ClassifyTest, classTaggingAndNeverSend)

[#3583] Added syntax UTs

[#3583] Addressred review comments

modified:
    doc/sphinx/arm/classify.rst
    src/bin/dhcp4/dhcp4_srv.cc
    src/bin/dhcp4/tests/config_parser_unittest.cc
    src/bin/dhcp6/tests/config_parser_unittest.cc
    src/hooks/dhcp/mysql/mysql_cb_dhcp4.cc
    src/lib/dhcp/classify.cc
    src/lib/dhcp/classify.h
    src/lib/dhcp/tests/classify_unittest.cc
    src/lib/dhcpsrv/cfg_option.cc
    src/lib/dhcpsrv/cfg_option.h
    src/lib/dhcpsrv/parsers/option_data_parser.cc
    src/lib/dhcpsrv/parsers/simple_parser4.cc
    src/lib/dhcpsrv/parsers/simple_parser6.cc
    src/lib/dhcpsrv/tests/dhcp_parsers_unittest.cc
    src/lib/dhcpsrv/testutils/generic_backend_unittest.cc

[#3583] Fix lexers after rebase

modified:   src/bin/dhcp4/dhcp4_lexer.cc
modified:   src/bin/dhcp6/dhcp6_lexer.cc

[#3583] Fixed JSON error in ARM

modified:   arm/classify.rst

[#3583] Updated doc

/doc/examples/kea4/all-keys.json
/doc/examples/kea6/all-keys.json
    Added client-classes to option-data

/doc/sphinx/arm/classify.rst
    Added new section "Option Class-Tagging"

/doc/sphinx/arm/dhcp4-srv.rst
/doc/sphinx/arm/dhcp6-srv.rst
    Added notes with pointers to new section

[#3583] Amended ChangeLog for #3536

[#3583] Minor refactoring

Added ClientClasses::fromElement()

/src/hooks/dhcp/mysql_cb/mysql_cb_impl.cc
/src/hooks/dhcp/pgsql_cb/pgsql_cb_impl.cc

/src/lib/dhcp/classify.cc
/src/lib/dhcp/classify.h

/src/lib/dhcp/tests/classify_unittest.cc
    TEST(ClassifyTest, ClientClassesFromElement) - new test

[#3583] PgSQL CB V4 and V6 support option class tagging

/src/hooks/dhcp/pgsql_cb/pgsql_cb_dhcp4.cc
/src/hooks/dhcp/pgsql_cb/pgsql_cb_dhcp6.cc
/src/hooks/dhcp/pgsql_cb/pgsql_cb_impl.cc
/src/hooks/dhcp/pgsql_cb/pgsql_cb_impl.h
/src/hooks/dhcp/pgsql_cb/pgsql_query_macros_dhcp.h

[#3583] MySQL CB V6 supports option class tagging

/src/hooks/dhcp/mysql_cb/mysql_cb_dhcp6.cc
/src/hooks/dhcp/mysql_cb/mysql_query_macros_dhcp.h

/src/lib/dhcpsrv/testutils/generic_cb_dhcp4_unittest.cc
/src/lib/dhcpsrv/testutils/generic_cb_dhcp6_unittest.cc
    Add classes to test options, change how test options are
    added to preserve client_classes and user_context

[#3583] MySQL CB V4 supports option class tagging

/src/hooks/dhcp/mysql_cb/mysql_cb_dhcp4.cc
/src/hooks/dhcp/mysql_cb/mysql_cb_impl.cc
/src/hooks/dhcp/mysql_cb/mysql_cb_impl.h
/src/hooks/dhcp/mysql_cb/mysql_query_macros_dhcp.h
/src/lib/config_backend/constants.h
/src/lib/dhcpsrv/testutils/generic_cb_dhcp4_unittest.cc

[#3583] add client_classes to option tables

/src/share/database/scripts/mysql/upgrade_025_to_026.sh.in
/src/share/database/scripts/pgsql/upgrade_025_to_026.sh.in
    - new files

/src/share/database/scripts/mysql/dhcpdb_create.mysql
/src/share/database/scripts/pgsql/dhcpdb_create.pgsql
    - adds client_classes to option tables

/configure.ac
/src/share/database/scripts/mysql/.gitignore
/src/share/database/scripts/mysql/Makefile.am
/src/share/database/scripts/pgsql/.gitignore
/src/share/database/scripts/pgsql/Makefile.am
    - added new upgrade files

/src/bin/admin/tests/pgsql_tests.sh.in
/src/bin/admin/tests/mysql_tests.sh.in
    - Updated for new schema 26

/src/lib/mysql/mysql_constants.h
/src/lib/pgsql/pgsql_connection.h
     Updated schema version

[#3583] kea-dhcp6 now supports option class tagging

/src/bin/dhcp4/tests/classify_unittest.cc
    Clean up of new tests.

/src/bin/dhcp6/dhcp6_srv.cc
    Dhcpv6Srv::appendRequestedOptions()
    Dhcpv6Srv::appendRequestedVendorOptions()
    - check OptionDescriptor::allowedForClientClasses()

/src/bin/dhcp6/tests/classify_unittests.cc
    TEST_F(ClassifyTest, requestedOptionClassTag)
    TEST_F(ClassifyTest, vendorClassOptionClassTag)
    TEST_F(ClassifyTest, persistedVendorOptsOptionClassTag)
    TEST_F(ClassifyTest, requestedVendorOptionsClassTag)

[#3583] kea-dhcp4 now supports option class tagging

/src/bin/dhcp4/dhcp4_srv.cc
    Dhcpv4Srv::appendServerID() - modified to use the standard
    option defintion when appending a generated server id.

    Dhcpv4Srv::appendRequestedOptions()
    Dhcpv4Srv::appendRequestedVendorOptions()
    Dhcpv4Srv::appendBasicOptions()
    - modified to OptionDescriptor::allowedForClientClasses()

/src/bin/dhcp4/tests/classify_unittest.cc
    TEST_F(ClassifyTest, requestedOptionClassTagTest)
    TEST_F(ClassifyTest, vendorOptionClassTagTest)
    TEST_F(ClassifyTest, vivcoOptionClassTagTest)
    TEST_F(ClassifyTest, vivsoOptionClassTagTest)
    TEST_F(ClassifyTest, basicOptionClassTagTest)
    - new tests

/src/bin/dhcp4/tests/dhcp4_srv_unittest.cc
    TEST_F(Dhcpv4SrvTest, appendServerID) - updated test

/src/bin/dhcp4/tests/dhcp4_test_utils.*
    Dhcpv4SrvTest::checkServerIdentifier() - new function

/src/lib/dhcpsrv/cfg_option.*
    OptionDescriptor::allowedForClientClasses() - new function

/src/lib/dhcpsrv/tests/cfg_option_unittest.cc
    TEST(OptionDescriptorTest, allowedForClientClassesTest) - new test

[#3583] Added client-class to OptionDescriptor

option-data.client-classes can be parsed and
stored in OptionDescriptor.

/src/bin/dhcp4/dhcp4_lexer.ll
/src/bin/dhcp4/dhcp4_parser.yy

/src/bin/dhcp6/dhcp6_lexer.ll
/src/bin/dhcp6/dhcp6_parser.yy

/src/lib/dhcp/classify.*
    Added ClientClasses copy and equality operators

/src/lib/dhcp/tests/classify_unittest.cc
    Udpated unit tests

/src/lib/dhcpsrv/cfg_option.cc
    Added OptionDecription::client_classes_ and supporting funcs

/src/lib/dhcpsrv/parsers/option_data_parser.cc
    OptionDataParser::createOption() - modified to parse 'client-classes'

/src/lib/dhcpsrv/parsers/simple_parser4.cc
    Added 'client-classes' to OPTION4_PARAMETERS

/src/lib/dhcpsrv/parsers/simple_parser6.cc
    Added 'client-classes' to OPTION6_PARAMETERS

/src/lib/dhcpsrv/tests/cfg_option_unittest.cc
    Updated tests

/src/lib/dhcpsrv/tests/dhcp_parsers_unittest.cc
    TEST_F(ParseConfigTest, optionDataClientClasses4)
    TEST_F(ParseConfigTest, optionDataClientClasses6)
    TEST_F(ParseConfigTest, optionDataClientClassesEmpty4)
    TEST_F(ParseConfigTest, optionDataClientClassesEmpty6)
    - new tests

[#3552] Addressed comments

[#3552] Fixed rebase

[#3552] Updated ChangeLog entry

[#3552] Revamped configure code

[#3552] Added a ChangeLog entry

[#3552] Updated Botan support

[#3588] Improved no test logs

[#3588] Removed useless check

[#3588] Addressed comments

[#3588] Modified no test required classes

[#3585] Completed changelog

[#3585] Added config in changelog

[#3585] Added a ChangeLog entry

[#3585] Regen flex/bison

[#3585] Updated syntax

[#3586] fixed typos

[#3586] reverted table widthwq

[#3586] fixed loggers table

[#3586] addressed review comments

[#3586] updated documentation

[#3594] added ChangeLog entry

[#3594] updated ARM

[#3594] deprecate output_options

[#3594] accept output-options or output_options in log parser

[#3606] Disabled forceUDPSendFailure on macOS

[#3590] Finished required precedence update

[#3590] Checkpoint: updated unit tests

[#3590] Checkpoint: reversed required order

[#3536] added ChangeLog entry

[#3536] use only one loger on load and unload

[#3536] removed more duplicated messages

[#3536] add crypto ligs to mysql and pgsql

[#3536] fix check-messages

[#3536] fixed log level in mes files

[#3536] updated examples

[#3536] addressed review comments

[#3536] moved log messages and loggers

[#3536] merge mysql and pgsql hooks

[#3536] refactor getDBVersions

[#3536] removed empty line in getDBVersions

[#3536] addressed comments

[#3536] wrap long lines

[#3536] add namespace to .mes files

[#3536] remove Initializer

[#3536] implement getDBVersion

[#3536] enable unittests

[#3536] fixed unittests by disabling configs

[#3536] remove HAVE_MYSQL and HAVE_PGSQL

[#3536] added hook callouts

[#3565] Added ChangeLog for #3565

[#3565] Prevent declining expired and released

[#3578] addressed review comments

[#3578] added more UTs to config_parser_unittest

[#3578] addressed review comments

[#3578] reverted changes

[#3578] added ChangeLog entry

[#3578] added tests in get_config_unittests

[#3578] removed disabled tests

[#3578] added load write and reload test

[#3390] Rebased and addressed comments

[#3390] Added a ChangeLog entry

[#3390] Completed split UT

[#3390] Checkpoint: doc and split

[#3390] Checkpoint: code done

[#3604] Bump up version in configure.ac to 2.7.4

[#3599] release changes

[#3600] check if message file is empty

[#3597] bump up library versions for 2.7.3 release

[#3576] fix indentation

[#3576] Addressed review comments

Moved UT, cleaned up test JSON

[#3576] Updated ARM, added ChangeLog

modified:
    ChangeLog
    doc/sphinx/arm/classify.rst

[#3576] Swap order of template and subclass

/src/bin/dhcp4/tests/dhcp4_srv_unittest.cc
    TEST_F(Dhcpv4SrvTest, subClassPrecedence) - new test

/src/bin/dhcp6/tests/classify_unittests.cc
    TEST_F(ClassifyTest, subClassPrecedence) - new test

/src/lib/dhcp/pkt.cc
    Pkt::addSubClass() - changed to add subclass then template to packet

/src/lib/dhcp/tests/pkt4_unittest.cc
    TEST_F(Pkt4Test, templateClasses) - test now verifies class order

/src/lib/dhcp/tests/pkt6_unittest.cc
    TEST_F(Pkt6Test, templateClasses) - test now verifies class order