diagnostics: move diagnostic_context to diagnostics::context in its own header

diagnostics: move diagnostic_context to diagnostics::context in its own header

No functional change intended.

gcc/ada/ChangeLog:
	* gcc-interface/misc.cc: Update for diagnostic_context becoming
	diagnostics::context.

gcc/analyzer/ChangeLog:
	* program-point.cc: : Update for diagnostic_context becoming
	diagnostics::context, and for diagnostic_source_print_policy
	becoming diagnostics::source_print_policy.

gcc/c-family/ChangeLog:
	* c-common.h: Update for diagnostic_context becoming
	diagnostics::context.
	* c-opts.cc: Likewise.

gcc/c/ChangeLog:
	* c-objc-common.cc: Update for diagnostic_context becoming
	diagnostics::context.
	* c-tree.h: Likewise.

gcc/ChangeLog:
	* coretypes.h: Update for diagnostic_context becoming
	diagnostics::context.
	* diagnostic-global-context.cc: Likewise.
	* diagnostic.cc: Likewise.  Also for diagnostic_option_classifier
	becoming diagnostics::option_classifier.
	* diagnostic.h (diagnostic_text_starter_fn): Rename to...
	(diagnostics::text_starter_fn): ...this, and move to
	diagnostics/context.h.
	(get_printer): Rename to...
	(diagnostics::get_printer): ...this, and move to
	diagnostics/context.h.
	(class diagnostic_option_manager): Rename to...
	(class diagnostics::option_manager): ...this, and move to
	diagnostics/context.h.
	(class diagnostic_option_classifier): Rename to...
	(class diagnostics::option_classifier): ...this, and move to
	diagnostics/context.h.
	(struct diagnostic_source_printing_options): Rename to...
	(struct diagnostics::source_printing_options): ...this, and move
	to diagnostics/context.h.
	(class diagnostic_column_policy): Rename to...
	(class diagnostics::column_policy): ...this, and move to
	diagnostics/context.h.
	(class diagnostic_location_print_policy): Rename to...
	(class diagnostics::location_print_policy): ...this, and move to
	diagnostics/context.h.
	(class html_label_writer): Rename to...
	(class diagnostics::html_label_writer): ...this, and move to
	diagnostics/context.h.
	(class diagnostic_source_print_policy): Rename to...
	(class diagnostics::source_print_policy): ...this, and move to
	diagnostics/context.h.
	(struct diagnostic_counters): Rename to...
	(struct diagnostics::counters): ...this, and move to
	diagnostics/context.h.
	(class diagnostic_context): Rename to...
	(class diagnostics::context): ...this, and move to
	diagnostics/context.h.
	(diagnostic_text_starter): Rename to...
	(diagnostics::text_starter): ...this, and move to
	diagnostics/context.h.
	(diagnostic_start_span): Rename to...
	(diagnostics::start_span): ...this, and move to
	diagnostics/context.h.
	(diagnostic_text_finalizer): Rename to...
	(diagnostics::text_finalizer): ...this, and move to
	diagnostics/context.h.
	Include "diagnostics/context.h".
	* diagnostics/buffering.h: Update for diagnostic_context becoming
	diagnostics::context; similarly for diagnostic_counters.
	* diagnostics/client-data-hooks.h: Likewise.
	* diagnostics/context.h: New file, taken from material in
	diagnostic.h.
	* diagnostics/html-sink.cc: : Update for diagnostic_context
	becoming diagnostics::context.
	* diagnostics/html-sink.h: Likewise.
	* diagnostics/lazy-paths.cc: Likewise for
	diagnostic_option_manager.
	* diagnostics/output-file.h: Likewise for diagnostic_context.
	* diagnostics/output-spec.cc: Likewise.
	* diagnostics/output-spec.h: Likewise.
	* diagnostics/paths-output.cc: Likewise.
	* diagnostics/sarif-sink.cc: Likewise.
	* diagnostics/sarif-sink.h: Likewise.
	* diagnostics/sink.h: Likewise.
	* diagnostics/source-printing.cc: Likewise.
	* diagnostics/text-sink.cc: Likewise.
	* diagnostics/text-sink.h: Likewise.
	* gcc-rich-location.h: Likewise.
	* gcc.cc: Likewise.
	* gdbinit.in: Likewise.
	* langhooks-def.h: Likewise.
	* langhooks.cc: Likewise.
	* langhooks.h: Likewise.
	* libgdiagnostics.cc: Likewise.
	* optc-gen.awk: Likewise.
	* opth-gen.awk: Likewise.
	* opts-common.cc: Likewise.
	* opts-diagnostic.cc: Likewise.
	* opts-diagnostic.h: Likewise.
	* opts-global.cc: Likewise.
	* opts.cc: Likewise.
	* opts.h: Likewise.
	* selftest-diagnostic.cc: Likewise.
	* selftest-diagnostic.h: Likewise.
	* toplev.cc: Likewise.
	* tree-diagnostic-client-data-hooks.cc: Likewise.
	* tree-diagnostic.cc: Likewise.
	* tree-diagnostic.h: Likewise.

gcc/cp/ChangeLog:
	* cp-tree.h: Update for diagnostic_context becoming
	diagnostics::context.
	* error.cc: Likewise.
	* module.cc: Likewise.

gcc/fortran/ChangeLog:
	* error.cc: Update for diagnostic_context becoming
	diagnostics::context.

gcc/jit/ChangeLog:
	* dummy-frontend.cc: Update for diagnostic_context becoming
	diagnostics::context.
	* jit-playback.h: Likewise.

gcc/rust/ChangeLog:
	* resolve/rust-ast-resolve-expr.cc: Update for diagnostic_text_finalizer
	becoming diagnostics::text_finalizer.
	* resolve/rust-late-name-resolver-2.0.cc: Likewise.

gcc/testsuite/ChangeLog:
	* g++.dg/plugin/show_template_tree_color_plugin.cc: Update for
	moves to namespace diagnostics.
	* gcc.dg/plugin/diagnostic_group_plugin.cc: Likewise.
	* gcc.dg/plugin/diagnostic_plugin_test_show_locus.cc: Likewise.
	* gcc.dg/plugin/location_overflow_plugin.cc: Likewise.

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