[llvm] [mlir] [mlir][core] Add an MLIR "pattern catalog" generator (PR #146228)

[Mehdi Amini via llvm-commits]

https://github.com/joker-eph commented:

That LGTM, but @jpienaar  is out for a few days and we should wait since he worked on an alternative.

https://github.com/llvm/llvm-project/pull/146228