Added OpInfo-based testing of some linalg functions (#51107)
Summary:
Added OpInfo-based testing of the following linear algebra functions:
* cholesky, linalg.cholesky
* linalg.eigh
* inverse, linalg.inv
* qr, linalg.qr
* solve
The output of `torch.linalg.pinv` for empty inputs was not differentiable, now it's fixed.
In some cases, batched grad checks are disabled because it doesn't work well with 0x0 matrices (see https://github.com/pytorch/pytorch/issues/50743#issuecomment-767376085).
Ref. https://github.com/pytorch/pytorch/issues/50006
Pull Request resolved: https://github.com/pytorch/pytorch/pull/51107
Reviewed By: albanD
Differential Revision: D27006115
Pulled By: mruberry
fbshipit-source-id: 3c1d00e3d506948da25d612fb114e6d4a478c5b1
