libgdiagnostics: sarif-replay: add extra sinks via -fdiagnostics-add-output= [PR11679...

libgdiagnostics: sarif-replay: add extra sinks via -fdiagnostics-add-output= [PR116792,PR116163]

This patch refactors the support for -fdiagnostics-add-output=SCHEME
from GCC's options parsing so that it is also available to
sarif-replay and to other clients of libgdiagnostics.

With this users of sarif-replay and other such tools can generate HTML
or SARIF as well as text output, using the same
  -fdiagnostics-add-output=SCHEME
as GCC.

As a test, the patch adds support for this option to the dg-lint
script below "contrib".  For example dg-lint can now generate text,
html, and sarif output via:

  LD_LIBRARY_PATH=../build/gcc/ \
    ./contrib/dg-lint/dg-lint \
	contrib/dg-lint/test-*.c \
	-fdiagnostics-add-output=experimental-html:file=dg-lint-tests.html \
        -fdiagnostics-add-output=sarif:file=dg-lint-tests.sarif

where the HTML output from dg-lint can be seen here:
  https://dmalcolm.fedorapeople.org/gcc/2025-06-20/dg-lint-tests.html
the sarif output here:
  https://dmalcolm.fedorapeople.org/gcc/2025-06-23/dg-lint-tests.sarif
and a screenshot of VS Code viewing the sarif output is here:
  https://dmalcolm.fedorapeople.org/gcc/2025-06-23/vscode-viewing-dg-lint-sarif-output.png

As well as allowing sarif-replay to generate HTML, this patch allows
sarif-replay to also generate SARIF.  Ideally this would faithfully
round-trip all the data, but it's not perfect (which I'm tracking as
PR sarif-replay/120792).

contrib/ChangeLog:
	PR other/116792
	PR testsuite/116163
	PR sarif-replay/120792
	* dg-lint/dg-lint: Add -fdiagnostics-add-output.
	* dg-lint/libgdiagnostics.py: Add
	diagnostic_manager_add_sink_from_spec.
	(Manager.add_sink_from_spec): New.

gcc/ChangeLog:
	PR other/116792
	PR testsuite/116163
	PR sarif-replay/120792
	* Makefile.in (OBJS-libcommon): Add diagnostic-output-spec.o.
	* diagnostic-format-html.cc (html_builder::html_builder): Ensure
	title is non-empty.
	* diagnostic-output-spec.cc: New file, taken from material in
	opts-diagnostic.cc.
	* diagnostic-output-spec.h: New file.
	* diagnostic.cc (diagnostic_context::set_main_input_filename):
	New.
	* diagnostic.h (diagnostic_context::set_main_input_filename): New
	decl.
	* doc/libgdiagnostics/topics/compatibility.rst
	(LIBGDIAGNOSTICS_ABI_2): New.
	* doc/libgdiagnostics/topics/diagnostic-manager.rst
	(diagnostic_manager_add_sink_from_spec): New.
	(diagnostic_manager_set_analysis_target): New.
	* libgdiagnostics++.h (manager::add_sink_from_spec): New.
	(manager::set_analysis_target): New.
	* libgdiagnostics.cc: Include "diagnostic-output-spec.h".
	(struct spec_context): New.
	(diagnostic_manager_add_sink_from_spec): New.
	(diagnostic_manager_set_analysis_target): New.
	* libgdiagnostics.h
	(LIBDIAGNOSTICS_HAVE_diagnostic_manager_add_sink_from_spec): New
	define.
	(diagnostic_manager_add_sink_from_spec): New decl.
	(LIBDIAGNOSTICS_HAVE_diagnostic_manager_set_analysis_target): New
	define.
	(diagnostic_manager_set_analysis_target): New decl.
	* libgdiagnostics.map (LIBGDIAGNOSTICS_ABI_2): New.
	* libsarifreplay.cc (sarif_replayer::handle_artifact_obj): Looks
	for "analysisTarget" in roles and call set_analysis_target using
	the artifact if found.
	* opts-diagnostic.cc: Refactor, moving material to
	diagnostic-output-spec.cc.
	(struct opt_spec_context): New.
	(handle_OPT_fdiagnostics_add_output_): Use opt_spec_context.
	(handle_OPT_fdiagnostics_set_output_): Likewise.
	* sarif-replay.cc: Define INCLUDE_STRING.
	(struct options): Add m_extra_output_specs.
	(usage_msg): Add -fdiagnostics-add-output=SCHEME.
	(str_starts_with): New.
	(parse_options): Add -fdiagnostics-add-output=SCHEME.
	(main): Likewise.
	* selftest-run-tests.cc (selftest::run_tests): Call
	diagnostic_output_spec_cc_tests rather than
	opts_diagnostic_cc_tests.
	* selftest.h (selftest::diagnostic_output_spec_cc_tests):
	Replace...
	(selftest::opts_diagnostic_cc_tests): ...this.

gcc/testsuite/ChangeLog:
	PR other/116792
	PR testsuite/116163
	PR sarif-replay/120792
	* sarif-replay.dg/2.1.0-valid/signal-1-check-html.py: New test
	script.
	* sarif-replay.dg/2.1.0-valid/signal-1.c.sarif: Add html and sarif
	generation to options.  Invoke the new script to verify that HTML
	and SARIF is generated.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>