swift234

[SourceKit] Stub in a new "fully_annotated_decl" field to cursor info

This will eventually replace the existing annoteded_decl for cursor
info, and be added to doc info as well.  For now put in under a
different field name to not break existing clients.

For now, just reimplement the existing annotations but put in tag names
that are specific to the kind of type/decl. The goal is to fill in a
lot more substructure/detail over time.

Incidentally flesh out some cursor info tests.

rdar://problem/24292226