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

[Sergey Shcherbinin via llvm-commits]

SergeyShch01 wrote:

Rebased onto the latest `upstream/main` and made the following changes:
- Switched from backpatching to buffered payload writing to improve typified profile writing performance.
- Hardened typified profile parsing and diagnostics.
- Added typified section inspection to `llvm-profdata`.
- Fixed mixed legacy/typified section handling.
- Expanded documentation and test coverage.

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