Added OpInfo for torch.einsum (#56276)
Summary:
Adds OpInfo testing for torch.einsum.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56276
Reviewed By: mruberry
Differential Revision: D27967095
Pulled By: heitorschueroff
fbshipit-source-id: 60524273d2ca885e7eeb932db3e7fd697ae5ca8e
