Since it's also used in the rust module, it should be in a common place.
Also rename from `TEST_KWARGS` to `TEST_KWS`, which is more in line with
the `*_KW` naming scheme used in the type_checking module.
Strictly speaking code restructuring isn't needed, but making this PEP8
compliant results in indentation of the code that reduces the
readability. By moving the offending code on the outside of the method
call, the readability is maintained.
Thanks to `ModuleInfo`, all modules are just named `foo.py` instead of
`unstable_foo.py`, which simplifies the import method a bit. This also
allows for accurate FeatureNew/FeatureDeprecated use, as we know when
the module was added and if/when it was stabilized.
Eli Schwartz