Port CPU torch.ormqr to ATen (#57315)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/57315
This PR ports `torch.ormqr` from TH to ATen.
CUDA path will be implemented in a follow-up PR.
With ATen port, support for complex and batched inputs is added.
The tests are rewritten and OpInfo entry is added.
We can implement the least squares solver with geqrf + ormqr +
triangular_solve. So it's useful to have this function renewed at least for the
internal code.
Resolves https://github.com/pytorch/pytorch/issues/24748
Test Plan: Imported from OSS
Reviewed By: ngimel
Differential Revision: D28242070
Pulled By: mruberry
fbshipit-source-id: f070bb6ac2f5a3269b163b22f7354e9089ed3061
