ns for fx: add qat handling for weight extraction (#55506)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55506
Makes the NS weight extraction tests also test QAT, and fixes
the mappings where necessary to cover all the fusions and make
the tests pass.
Test Plan:
```
python test/test_quantization.py TestFXNumericSuiteCoreAPIs.test_extract_weights_mod_ptq
python test/test_quantization.py TestFXNumericSuiteCoreAPIs.test_extract_weights_mod_qat
```
Imported from OSS
Reviewed By: jerryzh168
Differential Revision: D27650409
fbshipit-source-id: c5bd9268d1bc559afc27d4c5109effd77bf1538a
