Allow assigning a queue manager separate from the ticket owners
We should be able to designate one or more persons as the manager of a queue, separate from assigning them to the "Owners" list. It is quite common for there to be a help desk manager who supervises the team, but does not handle tickets directly.
Such an assigned manager should have full visibility into dashboard statistics, receive notifications of SLA violations, be able to assign/reassign or edit tickets, etc.
