let user skip printing command description

Close #9560: autodoc: Allow to refer NewType with modname in py310+

Before 3.10, an instance of NewType has incorrect module name. But it
was fixed on 3.10.  This starts to use the module info if the
interpreter is 3.10+.

Fix #9608: apidoc: module is not described if implicit namespace package

Fix #9600: autosummary: Typehints including commas confuses autosummary

To make implicit namespace packages referencable, this outputs empty
module definitions for them.