[llvm] [DAGCombiner] Share byte provider steps with AMDGPU target (PR #221959)

[Arseniy Obolenskiy via llvm-commits]

aobolensk wrote:

> I'm reluctant to rubber stamp on this because of the include of gigantic header `SelectionDAGNodes.h` in a very trivial helper header `llvm/include/llvm/CodeGen/ByteProvider.h`. I can see that the `ByteProvider.h` is only used in two cpp files where `SelectionDAGNodes.h` must have been included, but I'll still defer the decision to others.
> 
> Though, what is the problem of the old implementation that uses a template?

The template is gone after resolving this comment: https://github.com/llvm/llvm-project/pull/221959#discussion_r3958562295

Probably we should align the expectations on that

https://github.com/llvm/llvm-project/pull/221959