Add torch.linalg.cholesky_ex without checking for errors by default (#56724)
Summary:
The new function has the following signature `cholesky_ex(Tensor input, *, bool check_errors=False) -> (Tensor L, Tensor infos)`. When `check_errors=True`, an error is thrown if the decomposition fails; `check_errors=False` - responsibility for checking the decomposition is on the user.
When `check_errors=False`, we don't have host-device memory transfers for checking the values of the `info` tensor.
Rewrote the internal code for `torch.linalg.cholesky`. Added `cholesky_stub` dispatch. `linalg_cholesky` is implemented using calls to `linalg_cholesky_ex` now.
Resolves https://github.com/pytorch/pytorch/issues/57032.
Ref. https://github.com/pytorch/pytorch/issues/34272, https://github.com/pytorch/pytorch/issues/47608, https://github.com/pytorch/pytorch/issues/47953
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56724
Reviewed By: ngimel
Differential Revision: D27960176
Pulled By: mruberry
fbshipit-source-id: f05f3d5d9b4aa444e41c4eec48ad9a9b6fd5dfa5
