[NFC][InstrProf]Generalize getParsedIRPGOFuncName to getParsedIRPGOName (#81054)

- Function getParsedIRPGOFuncName splits name by delimiter. The `[filename;]mangled-name` format could be generalized for non-function global values (e.g., vtables for type profiling). So rename the
function.
- Use kGlobalIdentifierDelimiter rather than semicolon directly for defragmentation.