[clang] [sanitizer] Add plumbing for -fsanitize-add-pseudo-functions and partly replace '-mllvm -array-bounds-pseudofn' (PR #138577)

[Dan Liew via cfe-commits]

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

Seems reasonable. My main issue is the "add pseudo functions" name which isn't clear and isn't documented.

https://github.com/llvm/llvm-project/pull/138577