[llvm] [mlir] [MLIR][Python] reland (narrower) type stub generation (PR #157930)

[Ingo Müller via llvm-commits]

ingomueller-net wrote:

Minimal progress: I found that the following manually-specified signature allows `pyright` to continue to report all other errors (most of which I consider correctly detected problems, exception below):

```python
def register_operation(dialect_class: type[T], *, replace: bool = False) -> type[T]:
```

I don't know how to handle the closely related `error: Import symbol "X" has type "type[Y]", which is not assignable to declared type "type[Z]"`, though, which is also still reported.

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