Bug: 74831546 TransitionSet interpolator was never being used in child transitions. This transfers the interpolator by setting the interpolator of the children as they are added or when the interpolator is set. It also works for other settings: epicenter, path motion, and propagation. Test: Ie8ce23fe15e6193fdb2909606e442bd2912a4c5a Change-Id: Ia9e35639f025d14c6497fa30abf75252ff3b1423