[llvm] [TableGen][DecoderEmitter] Add option to emit type-specialized `decodeToMCInst` (PR #146593)

[Rahul Joshi via llvm-commits]

jurahul wrote:

Please see the PR description that I just added. I also have data to support this, will add soon (tabulating it ATM)

https://github.com/llvm/llvm-project/pull/146593