Remember the last (few) selected identity provider(s)

Currently, the CRDM disco service is geared a lot towards TU Wien employees (which is fair, I suppose).

However, for externals it would still be nice to not have to look up their home organization every time they want to log in.

This could probably be done via local storage. We don't need cookies for this, as the server doesn't have to know about the user's settings.

mentioned in merge request !3 (merged)

closed with merge request !3 (merged)