CUDA BFloat16 unary ops part 1 (#44813)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/44813
Reviewed By: mruberry
Differential Revision: D23805816
Pulled By: ngimel
fbshipit-source-id: 28c645dc31f094c8b6c3d3803f0b4152f0475a64
