Add test for empty tensors for batch matmuls (#47700)
Summary:
Fixes #{issue number}
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47700
Reviewed By: malfet
Differential Revision: D24874754
Pulled By: ngimel
fbshipit-source-id: 41ba837740ff7d5bd49d5f7277ad2064985aba2f
