[special] migrate log_softmax (#60512)
Summary:
Reference: https://github.com/pytorch/pytorch/issues/50345
Rendered Docs: https://14335157-65600975-gh.circle-artifacts.com/0/docs/special.html#torch.special.log_softmax
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60512
Reviewed By: iramazanli
Differential Revision: D29626262
Pulled By: mruberry
fbshipit-source-id: c42d4105531ffb004f11f1ba6ae50be19bc02c91
