Reland "[TypeProf][InstrPGO] Introduce raw and instr profile format change for...

Reland "[TypeProf][InstrPGO] Introduce raw and instr profile format change for type profiling." (#82711)

New change on top of [reviewed
patch](https://github.com/llvm/llvm-project/pull/81691) are [in commits
after this
one](https://github.com/llvm/llvm-project/pull/82711/commits/d0757f46b3e3865b5f7c552bc0744309a363e0ac).
Previous commits are restored from the remote branch with timestamps.

1. Fix build breakage for non-ELF platforms, by defining the missing
functions {`__llvm_profile_begin_vtables`, `__llvm_profile_end_vtables`,
`__llvm_profile_begin_vtabnames `, `__llvm_profile_end_vtabnames`}
everywhere.
* Tested on mac laptop (for darwins) and Windows. Specifically,
functions in `InstrProfilingPlatformWindows.c` returns `NULL` to make it
more explicit that type prof isn't supported; see comments for the
reason.
* For the rest (AIX, other), mostly follow existing examples (like this
[one](https://github.com/llvm/llvm-project/commit/f95b2f1acf1171abb0d00089fd4c9238753847e3))
   
2. Rena...