Add forward AD formulas for some losses (#71026)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71026
...and fmod
Testing:
- L1Loss: new module tests (linear in the real case only)
- SmoothL1Loss: new module tests
- MSELoss: tested - OpInfo + new module tests
- huberloss: tested - OpInfo + new module tests
- multi-margin-loss: new module tests
- kl-div: OpInfo + new module tests
- fmod: OpInfo
Test Plan: Imported from OSS
Reviewed By: albanD
Differential Revision: D33485661
Pulled By: soulitzer
fbshipit-source-id: 542ef5148183b9f574d06b2e2e345d0d889537b7
(cherry picked from commit 60765438e8de82cf9dd2fca71f2ae218c0a38493)
