卸载捆绑包中的所有资源。
卸载操作将释放与捆绑包中的对象关联的所有内存。
当 unloadAllLoadedObjects 为 false 时，将卸载捆绑包中资源的压缩文件数据，
但已从该捆绑包中加载的任何实际对象将保持不变。当然，您将无法再从该捆绑包加载任何其他对象。
When unloadAllLoadedObjects is true, all objects that were loaded from this bundle will be destroyed as well. If there are game
objects in your Scene referencing those assets, the references to them will become missing.