UMovieSceneReplaceableActorBinding

An implementation of [UMovieSceneReplaceableBindingBase](API\Runtime\MovieScene\UMovieSceneReplaceableBindingBas-) that uses [UMovieSceneSpawnableActorBinding](API\Runtime\MovieSceneTracks\UMovieSceneSpawnableActorBinding) as the preview spawnable, and has no implementation of ResolveRuntimeBindingInternal, relying instead of Sequencer's built in BindingOverride mechanism for binding at runtime.