[clang] [LifetimeSafety] Add support for GSL Pointer types (PR #154009)

[Utkarsh Saxena via cfe-commits]

usx95 wrote:

I think we have a very different model of understanding when a loan is created so it is hard to match these. Is there any piece specifically you have in mind. 

I could imagine lot of implicit annotation and annotation presence check can be shared (`shouldTrackImplicitObjectArg`, `isPointerLikeType`).

In general, I am a bit hesitant to share and widely use heuristics from the stmt-local analysis. I am ok with doing it for annotation semantics, implicit additions of annotations.

https://github.com/llvm/llvm-project/pull/154009