Membership migration requires some handwork

While users are still created, Member objects are not. This is really about Memberships. The old website had an enum instead of a proper history. This is a problem, in particular for things like the photos app that rely on these for permissions.

The solution is obvious: someone needs to sit down and type all the data from the physical binder into the database. That could be a few weeks of work though.

As an intermediate solution, we now set the membership of every member (or sponsor) to date.now() during the migration. This means that the date is clearly recognisable, and that members have an actual valid membership. It presents issues when memberships end and are not renewed.