batch size 0 tests in BatchMatMul ops (#26874)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/26874
Add batch_size == 0 testings of BatchMatMul DNNLOWP operator.
Test Plan: CI
Reviewed By: jianyuh
Differential Revision: D17596117
fbshipit-source-id: 029e29e6c2bd7894d83dac46e8ce8484cc92b1c0
