Updates QtQueueControl.py to change all pause operations to be deferred

This merge request changes all re_pause requests to use "deferred" instead of "immediate".

Context

When we are performing a scan or some operation with the RunEngine various motors are moved from one position to another and various detectors are triggered and read. It is common for a device to be in an undetermined state between one position an another, or while being triggered. If stopped during this operation then you might have to do special stuff to recover.

An example (and the thing that triggered this merge request) is a pseudo motor like a DCM energy and height motor. If the energy is being moved between A and B, then during the motion the height motor will move away from it's defined position and then back again at the end. If the energy motor is stopped during the move then the height motor will also be stopped and will be left in a position other than the one desired. When we request a plan to stop before it has finished, we should wait for all motors to reach where they are going first.

Why is this relevant? Users commonly stop a running plan when they realize the parameters are wrong. If they resume again, they expect things to be as they were when stopping.

This change doesn't come for free, now everything will take longer to stop, but it will be stopped in a safer way.