[clang] [clang][-Wunsafe-buffer-usage] Warn on annotated unsafe container construction (PR #227108)

[Ziqing Luo via cfe-commits]

https://github.com/ziqingluo-90 approved this pull request.

LGTM, thank you for this improvement and the explanation of your design choice. 

https://github.com/llvm/llvm-project/pull/227108