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

This patch adds `clang::preferred_type` annotations to Type-related bit-fields. At the moment only debug info takes advantage of this annotation. See more in https://github.com/llvm/llvm-project/pull/69104

This patch also propagates underlying type of several enums from bit-field declaration to enum declaration. I don't see how having them diverge helps.