[llvm] [TableGen] Emit Debug code for dynamic bits(eg: instruction operands) in DecoderEmitter (PR #194699)

[Sam Elliott via llvm-commits]

lenary wrote:

I think if this size is too large (I don't know what too large is, and what the overhead of this is, I am somewhat reserving judgement), then we ask backends to do this logging in their own decode functions manually. I guess they don't have the bool output of `Check` but iirc that's a reasonably simple conversion, so logging in the backend should be straightforward. 

https://github.com/llvm/llvm-project/pull/194699