Expose dist.monitored_barrier() API (#53787)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53787
Per title, exposes a python-based monitored barrier API that we can use as part of debugability and may be useful for user applications.
ghstack-source-id: 125124315
Test Plan: CI
Reviewed By: zhaojuanmao
Differential Revision: D26965127
fbshipit-source-id: 6c7826e63758462e3e5111f28cced54cba76a758
