[numpy] add torch.argwhere (#64257)
Summary:
Adds `torch.argwhere` as an alias to `torch.nonzero`
Currently, `torch.nonzero` is actually provides equivalent functionality to `np.argwhere`.
From NumPy docs,
> np.argwhere(a) is almost the same as np.transpose(np.nonzero(a)), but produces a result of the correct shape for a 0D array.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64257
Reviewed By: dagitses
Differential Revision: D31474901
Pulled By: saketh-are
fbshipit-source-id: 335327a4986fa327da74e1fb8624cc1e56959c70
