[#3830] Backport CVE-2025-32801 to v2_4

[#3830] Backport CVE-2025-32801 to v2_4

modified:   doc/sphinx/arm/hooks.rst
modified:   src/bin/agent/tests/ca_cfg_mgr_unittests.cc
modified:   src/bin/agent/tests/get_config_unittest.cc
modified:   src/bin/agent/tests/test_callout_libraries.h.in
modified:   src/bin/d2/tests/d2_cfg_mgr_unittests.cc
modified:   src/bin/d2/tests/d2_process_tests.sh.in
modified:   src/bin/d2/tests/d2_process_unittests.cc
modified:   src/bin/d2/tests/get_config_unittest.cc
modified:   src/bin/d2/tests/test_callout_libraries.h.in
modified:   src/bin/d2/tests/test_configured_libraries.h.in
modified:   src/bin/dhcp4/tests/config_parser_unittest.cc
modified:   src/bin/dhcp4/tests/ctrl_dhcp4_srv_unittest.cc
modified:   src/bin/dhcp4/tests/dhcp4_process_tests.sh.in
modified:   src/bin/dhcp4/tests/hooks_unittest.cc
modified:   src/bin/dhcp4/tests/test_libraries.h.in
modified:   src/bin/dhcp6/tests/config_parser_unittest.cc
modified:   src/bin/dhcp6/tests/ctrl_dhcp6_srv_unittest.cc
modified:   src/bin/dhcp6/tests/dhcp6_process_tests.sh.in
modified:   src/bin/dhcp6/tests/hooks_unittest.cc
modified:   src/bin/dhcp6/tests/test_libraries.h.in
modified:   src/lib/dhcpsrv/tests/Makefile.am
modified:   src/lib/dhcpsrv/tests/dhcp_parsers_unittest.cc
modified:   src/lib/dhcpsrv/tests/test_libraries.h.in
modified:   src/lib/hooks/Makefile.am
modified:   src/lib/hooks/hooks_parser.cc
modified:   src/lib/hooks/hooks_parser.h
modified:   src/lib/hooks/tests/Makefile.am
modified:   src/lib/hooks/tests/hooks_manager_unittest.cc
modified:   src/lib/util/Makefile.am
new file:   src/lib/util/filesystem.cc
new file:   src/lib/util/filesystem.h
modified:   src/lib/util/tests/Makefile.am
new file:   src/lib/util/tests/filesystem_unittests.cc