Enable InterfaceState's copy operator

Author: rhaschke

core/include/moveit/task_constructor/storage.h

@@ -129,6 +129,7 @@ class InterfaceState
 	/// copy an existing InterfaceState, but not including incoming/outgoing trajectories
 	InterfaceState(const InterfaceState& other);
 	InterfaceState(InterfaceState&& other) = default;
+	InterfaceState& operator=(const InterfaceState& other) = default;
 
 	inline const planning_scene::PlanningSceneConstPtr& scene() const { return scene_; }
 	inline const Solutions& incomingTrajectories() const { return incoming_trajectories_; }