batch size 0 support in FC DNNLOWP operators (#26872)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/26872
Add batch_size == 0 handlings in int8 FC operators. Added associated test cases.
Test Plan: CI
Reviewed By: jianyuh
Differential Revision: D17595385
fbshipit-source-id: d271b7bdbaf723fd6dee6f194da8c7fdfeef5fa2
