[llvm] [NFC] In InstrProf, generalize helper functions to take 'GlobalObject'. They currently take 'Functions' as function parameters or have 'Func' in the name. (PR #70287)

[Mingming Liu via llvm-commits]

minglotus-6 wrote:

Per offline chat, 
- Added a static function `getIRPGOObjectName` and forwards `getIRPGOFuncName` to it.  This way existing callers of `getIRPGOFuncName` remains unchanged, and the semantic (func vs object) is clearer at callsite.
- Updated the comment of `getPGOFuncName`.

https://github.com/llvm/llvm-project/pull/70287