[clang] [analyzer][NFC] Introduce APSIntPtr, a safe wrapper of APSInt (1/4) (PR #120435)

[Balazs Benics via cfe-commits]

steakhal wrote:

Thank you @Xazax-hun for so swiftly reviewing all these PRs. It means a lot <3

https://github.com/llvm/llvm-project/pull/120435