[clang] [clang] Add support for MSVC force inline attrs (PR #185282)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman approved this pull request.

I think the behavior in the tests looks good to me, thank you! If Microsoft comes back and says they are doing something with `[[msvc::forceinline]]` on a statement, we can modify our diagnostic behavior once we have more understanding of what the construct means.

https://github.com/llvm/llvm-project/pull/185282