[Quant][fx] Added test for quint4x2 for fx graph mode quantization (#69846)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/69846
Test Plan:
In pytorch main dir, execute
to run the added test
Reviewed By: jbschlosser
Differential Revision: D33152672
Pulled By: dzdang
fbshipit-source-id: 89951fcd23e7061d6c51e9422540b5f584f893aa
