[Quant][fx][improvement] Added test for quint4x2 for fx graph mode quantization (reland PR 69846) (#72278)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/72278
Added a fx quint4x2 test
Test Plan:
In pytorch main dir, execute
```
python test/test_quantization.py TestQuantizeFxOps.test_embedding
```
Reviewed By: jerryzh168
Differential Revision: D33994546
Pulled By: dzdang
fbshipit-source-id: 3aa9117523893a6ce27f05103d421507640c1ab0
(cherry picked from commit 3c6557f36e095d549c71f0993fdefbf26b754d8f)