hardswish: enable for QAT (#36604)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/36604
Adds the logic to wrap the HardSwish module in FakeQuant
to support QAT.
Test Plan:
Added test to cover that this happens properly.
Imported from OSS
Differential Revision: D21045322
fbshipit-source-id: 8c46559ade58a5d5c56442285842627a3143eb0f