Support tracing GenericList (#15969)
Summary:
Treat GenericList similarly to tuples and TensorList: recursively unpack them and assignValueTrace accordingly. Also add interpreter support for ListUnpack on GenericList
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15969
Differential Revision: D13665139
Pulled By: jamesr66a
fbshipit-source-id: cd8cb3dd7475f424e48a69d217f2eac529df9f6a
