Autodoc is crashed if `inspect.signature` raises ValueError on
generating signature from a property of the class.  It seems the
original code re-raise the exception meaningless.  So this ignores it
even if raised.

The logging module is crashed when the target object is a broken
metaclass that raises a TypeError on `isinstance()`.

This adds a workaround code to avoid the error.

GenericAliasMixin should use `restify()` to render the metadata of
GenericAlias as py36 does.

doc: Add docs for napoleon_preprocess_types

The old syntax will be deprecated in 4.x and 5.x and removed in Sphinx
6.0.