[dist_optim] add distributed functional Adam optimizer (#50624)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50624
Add TorchScript compatible Adam functional optimizer to distributed optimizer
Test Plan: Imported from OSS
Reviewed By: rohan-varma
Differential Revision: D25932770
Pulled By: wanchaol
fbshipit-source-id: cab3f1164c76186969c284a2c52481b79bbb7190
