Onboarding UI Refinement

Updates to the on boarding UI to bring it inline with mocks in Zeplin

Notes:

Site admin cards are added when needed.

The onboarding list collapses to a dropdown for status (future use implied) and the user stats are expanded by default.

Commit d22ab49 adds more interaction to the onboarding. As an admin completes a step, more of the site-admin cards are shown. For instance: when a user enables a repo they will see the "Explore" and "2 repositories" cards appear. This also solves the problem of hiding the user stats during setup because if an instance has less than 2 users, it won't show the stats.