[mlir:python] Set __module__ classes generated by nanobind adaptors.

This PR sets the `__module__` attribute of the classes generated by the
nanobind adaptors for attributes, types, and values (via
`mlir_(attribute|type|value)_subclass`). By default, the `__module__`
property is set to `importlib._bootstrap`, which isn't where we want the
new class to live. The new logic sets the property to the name of the
module provided as `scope` instead. This also makes nanobind's `stubgen`
generate stubs for those classes properly, which ignores classes whose
`__module__` does not correspond to the module it is generating stubs
for. This resolves #127518.

Signed-off-by: Ingo Müller <[email protected]>

Author: ingomueller-net

mlir/include/mlir/Bindings/Python/NanobindAdaptors.h

@@ -349,6 +349,7 @@ class pure_subclass {
     thisClass = metaclass(derivedClassName, nanobind::make_tuple(superClass),
                           attributes);
     scope.attr(derivedClassName) = thisClass;
+    thisClass.attr("__module__") = scope.attr("__name__");
   }
 
   template <typename Func, typename... Extra>