[clang-tools-extra] [clang-tidy] new check readability-mark-static (PR #90830)

[Carlos Galvez via cfe-commits]

carlosgalvezp wrote:

- I'm not sure this is so much a readability check, I'd put it in `misc`. The main problem that it solves is avoiding ODR violations. I'd call it `misc-prefer-internal-linkage`.
 
- The auto-fix should be configurable to choose `static` or anonymous namespace.


https://github.com/llvm/llvm-project/pull/90830