[c10d] Add debug level field in ProcessGroup (#56530)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56530
For upcoming diffs, ProcessGroup will need to know about debug level
for e.g. logging collective operations.
ghstack-source-id: 127535775
Test Plan: CI
Reviewed By: SciPioneer
Differential Revision: D27849839
fbshipit-source-id: a9f016a27d30a242eced19929b3824ae68fe430f
