[Model Averaging] Refactor averagers to accept parameters instead of a module (#62105)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/62105
This is for the preparation of wrapping the averager as an optimizer, which can only accept parameters rather than a module.
Proposal: https://github.com/pytorch/pytorch/issues/59699
ghstack-source-id: 134213572
Test Plan:
buck test mode/dev-nosan caffe2/test/distributed:distributed_nccl_fork -- test_periodic_model_averager
buck test mode/dev-nosan caffe2/test/distributed:distributed_nccl_fork -- test_average_parameters
Reviewed By: rohan-varma
Differential Revision: D29883693
fbshipit-source-id: 474ba924a0b05068b12f163fb74582bccf314964
