Add support for dragging transform gizmos for actors around while playing in editor

At the moment, you can play in the editor and eject. Select an actor and change its position via the details panel, while running. This is awesome for changing the target for an AI unit, while the editor is playing. However, you can’t move the actors transform gizmos around the same way. It is a bit of shame, as this is a natural extension of being able to modify the position in the actor details. Current it just snaps back.