LocomotionTurnerInteractable Class

Contractually, Interactor<TInteractor, TInteractable>s require interactables, but LocomotionTurnerInteractor's interaction (turning the user) doesn't logically require a target since it simply invokes a specific effect.

LocomotionTurnerInteractable is thus provided as an empty interactable type, no instances of which should ever be created, simply as an implementation detail of LocomotionTurnerInteractor.