[llvm] Reapply "[LLVM][TableGen] Parameterize NumToSkip in DecoderEmitter" (#136017) (PR #136019)

[Rahul Joshi via llvm-commits]

jurahul wrote:

Note: The assert condition is now `DestIdx >= FixupIdx + NumToSkipSizeInBytes`. This happens when we are skipping to the op right after the one being patched. The incorrect condition was `DestIdx > FixupIdx + NumToSkipSizeInBytes`. Verified by changing that assert to `PrintFatalError` and build AArch64GenDisassemblerTables.inc file. None of the pre-submit and local testing caught it was it all runs release builds of tablegen.

https://github.com/llvm/llvm-project/pull/136019