stubgen (stubgenc): Support for tp_getset style C properties

Feature

Currently for C extensions, attributes of a C type originating from tp_getset are not recognized as a class property.
It would be nice to still parse the docstring in such cases, to infer types.

Pitch

As far as I understand, this is due to mypy.stubgenc.is_c_property looking for the fget attribute (the tp_getset style attributes dont have such an attribute - at least in my case, python 3.8).

I am not sure how to properly add checks for such a case (is just removing the check hasattr(obj, 'fget') enough?)

Would be glad for any input here (Am I missing something? Is there a good strategy to add support for tp_getset style attributes?). I would offer to implement the feature, if you think this would make sense.

Comienza en mypy.stubgenc.is_c_property e inspecciona cómo stubgen reconoce las propiedades y lee sus docstrings. Determina en qué se diferencian los atributos de C de estilo tp_getset del caso existente y, a continuación, verifica que sus docstrings puedan utilizarse para inferir los tipos de las propiedades sin afectar a otros atributos de extensiones de C.