[llvm] [NFC][ARM][MC] Rearrange decoder functions 2/N (PR #155464)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

One idea came to me.
I think eventually we'll want to move all these functions into the ARMDisassembler class, along with the generated decodeInstruction/checkPredicate etc. Similar to ARMDAGToDAGISel.
When/if that happens, we will no longer need to move the definitions around, they will only need to be prefixed with `ARMDisassembler::` (and the last argument removed). There is a long road ahead though.


https://github.com/llvm/llvm-project/pull/155464