perf annotate: Add dso__debuginfo() helper

perf annotate: Add dso__debuginfo() helper

It'd be great if it can get the correct debug information using DSO
build-Id not just the path name.  Instead of adding new callsites of
debuginfo__new(), let's add dso__debuginfo() which can hide the access
using the pathname and help the future conversion.

Suggested-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250816031635.25318-12-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>