[clang] [llvm] [PGOVerify] Add end-to-end IPGOVerifier infrastructure, validations, and function filtering (PR #196295)

[Aiden Grossman via cfe-commits]

https://github.com/boomanaiden154 requested changes to this pull request.

There are unanswered questions in https://discourse.llvm.org/t/rfc-pass-instrumentation-based-verification-for-pgo-use-profile-consistency/90796?u=boomanaiden154-1 and it is still unclear how this integrates with profcheck.

https://github.com/llvm/llvm-project/pull/196295