Query param `mrPermission`

[XanderVertegaal]

The form and study queries (used in AvailableActions.vue, among others) require that the client pass a mrPermission argument. This feels unnecessary. The backend already determines which studies/forms the user is allowed to see, and whether a user is allowed to modify it is specified in study.actions. The frontend should not have to

I think the mrPermission argument can be removed or should at least be made optional. This is not a high-priority refactor.