Adds torch.linalg namespace (#42664)
Summary:
This PR adds the `torch.linalg` namespace as part of our continued effort to be more compatible with NumPy. The namespace is tested by adding a single function, `torch.linalg.outer`, and testing it in a new test suite, test_linalg.py. It follows the same pattern that https://github.com/pytorch/pytorch/pull/41911, which added the `torch.fft` namespace, did.
Future PRs will likely:
- add more functions to torch.linalg
- expand the testing done in test_linalg.py, including legacy functions, like torch.ger
- deprecate existing linalg functions outside of `torch.linalg` in preference to the new namespace
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42664
Reviewed By: ngimel
Differential Revision: D22991019
Pulled By: mruberry
fbshipit-source-id: 39258d9b116a916817b3588f160b141f956e5d0b
