[llvm] Introduction of Composite Profile section in ExtBinary format (PR #166553)

[Sergey Shcherbinin via llvm-commits]

SergeyShch01 wrote:

@snehasish, 

Thanks, addressed:
- Renamed Typified Profile to Composite Profile.
- Assigned composite sections ExtBinary version 105, so older readers reject them cleanly.
- Kept composite writing opt-in via --extbinary-composite-prof.
- The default writer continues emitting the existing legacy format.

https://github.com/llvm/llvm-project/pull/166553