Add progress spinner to organigram and room

[friedaxvictoria]

Same solution as in #674

[paule96]

and also for rooms please :) @DanielHabenicht can we just add an interceptor that runs before every xhr request and after? That's maybe simpler to catch everything. And don't display the spinner in the table. Just gray out the app and show a spinner on top of the app?

[DanielHabenicht]

You could but thats not really user friendly because you could have clicked wrong and just want to click another navigation button right away.

Of course, there could be a generalized component for loading and error handling, but for now, it might be easier to just copy.