TST: add option to skip ROQs tests
This MR adds a flag to test suite so one can run pytest --skip-roqs
to skip all tests marked with the mark pytest.mark.requires_roq
. This can be useful when running the tests on a machine that doesn't have the ROQ files downloaded.
I'm happy to change the exact names if people have suggestions. I also need to figure out the best way to test this since we don't want the CI skipping the tests.