[dist_optim] add distributed functional Adadelta optimizer (#50623)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/50623
Add TorchScript compatible Adadelta functional optimizer to distributed optimizer
Test Plan: Imported from OSS
Reviewed By: rohan-varma
Differential Revision: D25932772
Pulled By: wanchaol
fbshipit-source-id: d59b04e5f0b6bab7e0d1c5f68e66249a65958e0b
