[clang] [clang][analyzer] Move 'alpha.core.PointerSub' checker into 'core.PointerSub' (PR #107596)

[Balazs Benics via cfe-commits]

https://github.com/steakhal requested changes to this pull request.

I'm not satisfied with the quality of the reports. The report refers to `Subtraction of two pointers that do not point into the same array is undefined behavior` without pointing out where the two pointers point to (and/or where are they declared, or set to point to different objects). Without improving the diagnostics, I don't think we should move this out of alpha.

https://github.com/llvm/llvm-project/pull/107596