int8 fc with tests (#38017)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38017
added a more comprehensive set of tests for int8fc
there are some failures but this emulation gets us much closer than the
existing one
there is still more work coming in
Test Plan: the test itself
Reviewed By: amylittleyang
Differential Revision: D21368530
fbshipit-source-id: 318722c030b2a1f8de37adb7c8633f75057edfab
