Disable certain filters for certain users

[winged]

Some of the filters in Caluma are quite slow / resource hungry. Especially the ones evaluating JEXL in QUERY requests:

• Question.visibleInDocument
• QuestionOption.visibleInDocument

We should create some functionality to restrict queries depending on who's sending the request. Similar to the visibility layer, but for access to filters (Or also other GQL structures, like too-big queries etc).

We already do have some structure in place to catch these things in the form of the SuppressIntrospection validator, so it should not be too hard.