[llvm] [HLSL] Refactoring DXILABI.h to not depend on scope printer (PR #153840)

[Chris B via llvm-commits]

llvm-beanz wrote:

> Another alternative would be to fix the (I think) 3 cases of misused `to_underlying` that are modified in this PR, and subsequently fix all the others.

This is what I intended in my comment. We should not be changing lines of code from one wrong state to another wrong state. The use of to_underlying in the modified lines here is clearly wrong, so we should just fix it.

https://github.com/llvm/llvm-project/pull/153840