Fix timeouts when saving authority records

[danloveg]

Closes #2421

All events linked to an actor were being saved in a loop any time that actor was saved. This causes a performance hit especially when many events are linked to an actor. I found that saving all the events was unnecessary because existing events are already saved by the EventEditComponent when they're changed. The only events that need to be saved in QubitActor::save are newly created events, since those are not automatically saved by the event edit component. To improve performance:

• Instead of looping through every event linked to the actor and saving them, only save the events that are newly added.
• Instead of getting related object IDs by loading all event objects, query for them directly.