AsyncOperation Asynchronous unload request for an AssetBundle.
Unloads assets in the bundle.
When unloadAllLoadedObjects is false, compressed file data for assets inside the bundle will be unloaded, but any actual objects already loaded
from this bundle will be kept intact. After calling UnloadAsync on an AssetBundle, you cannot load any more objects from that bundle and other operations on the bundle will throw InvalidOperationException.
When unloadAllLoadedObjects is true, all objects that were loaded from this bundle will be destroyed as well. If there are GameObjects in your Scene referencing those assets, the references to them will become missing.