Add ONNX export support for torch.rand. (#20559)
Summary:
This PR adds support for torch.rand export in the PyTorch ONNX exporter. There are other generator ops that need to be supported for export and they will added in subsequent PRs. This op is needed with priority for a model on our end.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/20559
Differential Revision: D15379653
Pulled By: houseroad
fbshipit-source-id: d590db04a4cbb256c966f4010a9361ab8eb3ade3
