[llvm] [TableGen] Add `CodeGenIntrinsicsMap` for on-demand intrinsic creation (PR #107100)

[Rahul Joshi via llvm-commits]

jurahul wrote:

Note, the motivation for this is to add better error checking when the number of return values from an intrinsic exceeds what is supported. Once this is in, I'll capture that limit in the CodeGenIntrinsicContext and have the CodeGenIntrinsic constructor error out if the limit exceeds. Today this case spits out with a non-obvious error followed by a assert failure in cast<>. Likely a crash in release builds.

https://github.com/llvm/llvm-project/pull/107100