tests(e2e): add coverage for premium features

[aslilac]

We need to add coverage for our newly developed "premium" features to the e2e test suite now that support for testing them has landed in our e2e testing setup.

A minimal set of tests should look something like...

• tests(e2e): add crud tests for organizations #164
• tests(e2e): add crud tests for organization members #165
• tests(e2e): add a crud test for custom roles #166
• tests(e2e): add a crud test for organization groups #167

...and for bonus points, we could also...

• tests(e2e): run tests with multiple permission levels where appropriate #168
• tests(e2e): add a test for IdP export #169