playGroup method
播放指定分组的所有动画
Implementation
void playGroup(String label, {Duration? duration}) {
final group = _groups[label];
if (group != null) {
_groupCompletionStatus[label] = false;
for (final controller in group) {
_controllerCompletionStatus[controller] = false;
_playController(controller, duration: duration);
}
}
}