Blender Git Loki

Fix T92043: Relax/Push Pose does nothing for quaternion rotation.

As can be confirmed by checking generic code for this operation,
it is supposed to blend between the result of Breakdown based on
actual frame range, and the current pose. However for some reason
the quaternion specific code was blending between the current pose
and the current keyframed pose. This means that the operation does
nothing if invoked without modifying the pose first.

This rewrites the code to match the non-quaternion behavior.

Differential Revision: https://developer.blender.org/D13030