Add `itertools.{prod, combinations, combinations_with_replacement}` like op to pytorch (#9393)
Summary:
closes https://github.com/pytorch/pytorch/issues/7580
Pull Request resolved: https://github.com/pytorch/pytorch/pull/9393
Differential Revision: D13659628
Pulled By: zou3519
fbshipit-source-id: 3a233befa785709395a793ba8833413be394a6fd
