[clang] [clang][NFC] Annotate `Type` bit-fields with `clang::preferred_type` (PR #70349)

[Erich Keane via cfe-commits]

erichkeane wrote:

We definitely need to wrap these in a macro/hide them in a macro somehow.  This will fail `-Werror` on GCC/MSVC/Older Clang compilers.

https://github.com/llvm/llvm-project/pull/70349