[torch distributed] Implementing all_gather_base (#56315)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56315
This diff implements the all_gather_base in pytorch distributed.
Test Plan: dist.all_gather_base(output, input)...
Reviewed By: agolynski, amylittleyang
Differential Revision: D27488999
fbshipit-source-id: 937ec8bddf9527fa4d114f984d1d0f6a5b8c3936
