'onPanEnd' and 'onRotationEnd' callbacks does not work

[wangier]

'onPanEnd' and 'onRotationEnd' callbacks can't be triggered. I debuged into ar_object_manager.dart. the call.arguments map only has 'transform' entry, the 'name' entry does not exist. This would throw an exception of null conversion.

[nikkon404]

facing the same issue in iOS. The call.arguments has only transform but no name

[nikkon404]

I created a PR for that btw:
#31