[clang] [Sema] Suggest missing format attributes (PR #166738)

[via cfe-commits]

https://github.com/apple-fcloutier requested changes to this pull request.

Thanks for addressing the comments I had on the last iteration. I would mostly like us to resolve quality-of-life issues with -Wmissing-format-attribute and how it combines with other format warnings to proceed.

https://github.com/llvm/llvm-project/pull/166738