Integrate cpp.hint related features that are availble in VS

[Colengms]

VS has some features related to cpp.hint files (used to indicate syntax-impacting macros to the tag parser).

• Squiggles for macros likely missing hints
• Code actions to add macros to cpp.hint
• Command to dump list of tag parsing issues

The underlying support for some of these may rely on db population unification work.

[heartacker]

yes we
want it