在后续 time 秒的时间段内，使名称为 animation 的动画淡入，使其他动画淡出。
If mode is PlayMode.StopSameLayer, animations in the same layer as animation will be faded out while animation is faded in.
if mode is PlayMode.StopAll, all animations will be faded out while animation is faded in.
如果未将该动画设置为循环，则该动画在播放后将停止并倒回。