Rename test files to pytest form.
Translate repo test to pytest, including some minor refactoring.
Translate gateway test to pytest.
Remove fs_suite file and mark listed modules.

pytest does not use this form of suite. The nearest equivalent is marking
the relevant modules and then using that marker, e.g.

./setup.py test -s test -m fs_suite
Change setter for develop.
Catch a handful of missed self.fails
Mark develop-only permanent fails. See #11610
Merge pull request #1684 from ximenesuk/dev-only-pytest-fixes

Develop-only Python test fixes