FMassCommandAddFragmentInstancesAndResaveIAPersistence

Note: TManagerType is always expected to be [AInstancedActorsManager](API\Plugins\InstancedActors\AInstancedActorsManager), but is declared as template's param to maintain uniform command adding interface via [FMassCommandBuffer.PushCommand](API\Plugins\MassEntity\FMassCommandBuffer\PushCommand\4).