[clang] [llvm] [nfc]Generalize PGOFuncName helper methods for general global objects (PR #73570)

[Mingming Liu via cfe-commits]

minglotus-6 wrote:

Per offline discussion, I'm going to construct c program test cases (to generate raw profiles) to exercise the code path that annotates value profiles and extend https://github.com/llvm/llvm-project/blob/main/llvm/test/Transforms/PGOProfile/thinlto_indirect_call_promotion.ll.

I'll convert this to a draft and re-visit (to rename metadata name from `PGOFuncName` to `PGOName`).

https://github.com/llvm/llvm-project/pull/73570