[llvm] [mlir] [MLIR][Python] reland stubgen v2 (PR #157930)

[Maksim Levental via llvm-commits]

makslevental wrote:

Note this has been [tested against IREE](https://github.com/iree-org/iree/pull/21916) with @Hardcode84's help.

https://github.com/llvm/llvm-project/pull/157930