[c10d] Enable gather_object on nccl (#71623)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71623
Enable gather_object on the nccl backend, since we already support `dist.gather` on nccl. This requires user to set the current device properly.
ghstack-source-id: 147754836
Test Plan: distributed_nccl_spawn -r test_gather_object
Reviewed By: zou3519
Differential Revision: D33701042
fbshipit-source-id: 39cff22947a7cac69d0c923b956dc10f25353a6f
(cherry picked from commit 6e6eff497ff9ac4888ba1876740ac80ea1eb2201)
