[llvm] Reapply "[LLVM][TableGen] Parameterize NumToSkip in DecoderEmitter" (#136017) (PR #136019)

[Rahul Joshi via llvm-commits]

jurahul wrote:

Let me try. I ran into problems doing so I think due to AMDGPU's usage of this in a header file. But in my change, I am moving it to a header file anyway, so maybe that with anonymous namespace will do the trick.

https://github.com/llvm/llvm-project/pull/136019