[clang-tools-extra] [clang-tidy] Add new check `llvm-prefer-static-over-anonymous-namespace` (PR #142839)

[Carlos Galvez via cfe-commits]

carlosgalvezp wrote:

I agree with the sentiment that it would be good to have one single check enforcing either one style or the other, possibly a "readability" type of check. Then llvm could be an alias with the proper config. 

I suppose this patch does not impede further refactoring if we want to go in that direction in the future.

https://github.com/llvm/llvm-project/pull/142839