Add a GoalUpdatedController to BT Nodes

[SteveMacenski]

Essentially, if the goal is updated, allow the children to be ticked, analog to RateController or DistanceController but the triggering event is that the goal or goals BT blackboard variables are updated due to preemption or a new request.

That way, for instance, we could replan only when a new goal is requested. Add a BT XML showcasing this.

Also worth considering adding some goal updated logic in the default BT XMLs so that we can replan immediately on a goal change and not wait for the next replanning cycle due to time, distance, etc.

[SteveMacenski]

Output of discussion from #3022