[clang] [CIR] Add .clang-tidy files for ClangIR specific coding style rules (PR #111417)

[Nathan Lanza via cfe-commits]

lanza wrote:

> I am not familiar with how clang-tidy works. (I expect that will have to change and I should start using it.) So I can't meaningfully review this.

If you use clangd then the clang-tidy based warnings will just show up in your editor. These files are just enforcing the ClangIR specific rules. 

https://github.com/llvm/llvm-project/pull/111417