Add alias torch.negative to torch.neg. (#43400)
Summary:
xref https://github.com/pytorch/pytorch/issues/42515
Pull Request resolved: https://github.com/pytorch/pytorch/pull/43400
Reviewed By: albanD
Differential Revision: D23266011
Pulled By: mruberry
fbshipit-source-id: ca20b30d99206a255cf26438b09c3ca1f99445c6
