[quant][ao_migration] nn.intrinsic.qat migration to ao (#86171)
All quantization-related modules are being migrated to `torch.ao`. This migrates the `nn.intrinsic.qat`. Please, see the [tracker](https://github.com/pytorch/pytorch/issues/81667) for the timeline.
```
python test/test_quantization.py TestAOMigrationNNIntrinsic
```
Differential Revision: [D39419993](https://our.internmc.facebook.com/intern/diff/D39419993/)
**NOTE FOR REVIEWERS**: This PR has internal Meta-specific changes or comments, please review them on [Phabricator](https://our.internmc.facebook.com/intern/diff/D39419993/)!
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86171
Approved by: https://github.com/jerryzh168
