UInstancedActorsVisualizationSwitcherProcessor::SwitchEntityMeshDesc

Switch EntityHandle to NewStaticMeshDescHandle by removing any current / previous ISMC instances for the current StaticMeshDescIHandle and setting RepresentationFragment.PrevRepresentation = [EMassRepresentationType::None](API\Plugins\MassRepresentation\EMassRepresentationType) to let the subsequent [UMassStationaryISMSwitcherProcessor](API\Plugins\MassRepresentation\UMassStationaryISMSwitcherProces-) see that a new isntance needs to be added for the now set NewStaticMeshDescHandle