ns for fx: extend functional weight extraction testing to QAT (#55507)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55507
As titled, extends the test cases for weight extraction from
functionals to cover QAT.
Test Plan:
```
python test/test_quantization.py TestFXNumericSuiteCoreAPIs
```
Imported from OSS
Reviewed By: jerryzh168
Differential Revision: D27650408
fbshipit-source-id: 8ce87d56bbc0da7c2330ece71a897d6d8c5110a0
