[llvm] [AMDGPU][MC] Separate VOPC MnemonicAlias from Instruction (PR #89105)

[Joe Nash via llvm-commits]

Sisyph wrote:

> Can we just make a PredicateControl'd wrapper for aliases? I believe Mips does that, and I started to make that conversion at some point but never finished

I am making a stab at it. As you hinted at, it gets quite complicated, so I will certainly prefer to do it in a follow up patch. 

https://github.com/llvm/llvm-project/pull/89105