Limit the amount of booking staff can have when booked of behalf.
- Similar to a normal bookings, 1 per day per person.
- 1 booking via book on behalf functionality, per day.

Currently when using the book on behalf feature, the limitation is only capped at how many desks a user have access too.
e.g. I have access to 100 desk, I can book 100 desk to another staff member when and errors or issues.