This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
There are 4 visibility levels
- public (default)
- members only
- staff
- owners
Note, admins and group owners ALWAYS have visibility to groups
Migration treated old "non public" as "members only"