[clang] [clang][Sema] Deprecate `global`/`unknown` in `lifetime_capture_by` (PR #196635)

[Gábor Horváth via cfe-commits]

https://github.com/Xazax-hun approved this pull request.

This looks great! Sorry for the late response, your assumption was right! Thanks a lot for working on this! 

https://github.com/llvm/llvm-project/pull/196635