[CIR] Add .clang-tidy files for ClangIR specific coding style rules

[lanza]

https://llvm.github.io/clangir/GettingStarted/coding-guideline.html

[erichkeane]

I don't have a good idea of what the whole list should BE, but htis seems reasonable to me.

[dkolsen-pgi]

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.

[lanza]

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.