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

[Rahul Joshi via llvm-commits]

jurahul wrote:

[MC decoder impl vs no-impl perf data - Sheet2.pdf](https://github.com/user-attachments/files/21904649/MC.decoder.impl.vs.no-impl.perf.data.-.Sheet2.pdf)

Attaching the data as a PDF (not sure how to directly share it)

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