[Perspectives] Integrate into user management

[markus-moser]

The information which perspectives are available for a user and which perspective is the currently active one is stored in the user table for the perspectives in the classic bundle (perspectives and activePerspective columns).

We need to find a way to integrate the logic for the new perspectives too. Please keep in mind that it is needed to somehow make it possible that studio UI and classic bundle work in parallel. I'd say it's ok when setting the perspectives permissions is only possible in the related UI (so for classic bundle in classic bundle and for studio in studio). Not sure if extending the user entity in the core for studio is a good idea or if it would be better to create a new additional table within studio? With this approach we could keep the core clean from studio related things (and at some point after sunsetting the classic bundle we could deprecate the properties in the core...).

[markus-moser]

Related to #144