Calendar: add capabilities to booking request form

[melanietreitinger]

1. After the event has been processed by the servicetem, it can't be edited by the booking person.
   -> bookingstatus != NEW : event cannot be edited by the booking person any more.

2. When the booking person clicks on the event slot, a detailed view of the event opens.
   -> own events (created by me) and assigned events (examiner) can be viewed in detail. Other events cannot be viewed at all.

3. When the service team clicks on the event slot, a detailed view (reading and editing permitted) of the event opens.
   -> service team can view and edit everything anytime.

Role	See all details ov event	Edit all details of event
Service-Team	✅	✅
Booking person	only own events	❌
Examiners	only own events	❌
Others	no details	❌

[melanietreitinger]

Fixed in branch 55-calendar-add-capabilities-to-booking-request-form.

✔ This should work now!

✔ Code on test server has been updated.