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

[Rahul Joshi via llvm-commits]

jurahul wrote:

I realized that this is also fixing and/or avoiding potential future bugs where the code in PatternParser or SearchableTableEmitter today is not getting the right properties for the CodeGenIntrinsic objects created.

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