[clang-tools-extra] New check for static_cast of an enum class type (PR #167212)

[Yanzuo Liu via cfe-commits]

https://github.com/zwuis requested changes to this pull request.

Please finish https://github.com/llvm/llvm-project/issues/71543#issuecomment-3171781147.

https://github.com/llvm/llvm-project/pull/167212