Move THCTensor_{random, clampedRandom, cappedRandom} to ATen (#20620)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20620
ghimport-source-id: 7c09c2462021e3fa5adef61570a575964ff16125
Differential Revision: D15454050
Pulled By: ezyang
fbshipit-source-id: 5b0421c56445baf19dbdbdd9680af128a5cdf443
