Adapt current activity & approval system to new status categories

[julianweng]

Club status is currently implied from a combination of the ghost field, active field, approved field, and archived field. There are two options in adapting this to the new categories provided.

1. Providing a helper utility on the backend that assigns category names to the corresponding combinations of these fields for use in the frontend, and also validates club statuses at all times to ensure the invariant that the club fits in one of these categories
2. Converting all of these fields into a single enum field