[clang] [clang] callee_type metadata for indirect calls (PR #163233)

[Paul Kirth via cfe-commits]

https://github.com/ilovepi approved this pull request.

Largely I think this is in pretty decent shape. Tests seem much improved, and the patch is a lot more focused IMO. Please check that @arsenm before landing, since IIRC he had a concern w/ the use of `hasAddressTaken()`. 

https://github.com/llvm/llvm-project/pull/163233