Introduce a robot queuing system

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There are cases where multiple mobile robots may be simultaneously blocked waiting for the same resource, such as a lift, workcell, or access to a pickup/dropoff point. In those cases it is useful to have a formal queuing system that allows the robots to smoothly and consistently approach the resource 1-by-1 as it becomes available to each of them.

We should develop a queuing system by first developing the reservation system and then integrating the reservation capabilities with the traffic planner. We should also add a feature to the traffic editor that allows system integrators to graphically define what the queuing behavior should be.