Create PyTorch DDP logging APIs for applications to use (#50637)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50637
add APIs for logging pytorch ddp logging data in applications.
Test Plan: unit tests
Reviewed By: rohan-varma
Differential Revision: D25933411
fbshipit-source-id: 57c248a2f002da06a386fc7406d3e5533ebb9124
