Add native_dropout (#63937)
Summary:
Adds native_dropout to have a reasonable target for torchscript in auto diff. native_dropout has scale and train as arguments in its signature, this makes native_dropout more consistent with other operators and removes conditionals in the autodiff definition.
cc gmagogsfm
Pull Request resolved: https://github.com/pytorch/pytorch/pull/63937
Reviewed By: mruberry
Differential Revision: D32477657
Pulled By: ngimel
fbshipit-source-id: d37b137a37acafa50990f60c77f5cea2818454e4
