groupnorm: eager mode QAT support (#39092)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/39092
Adds eager mode QAT support for GroupNorm.
Test Plan:
```
python test/test_quantization.py TestQuantizationAwareTraining.test_normalization
```
Imported from OSS
Differential Revision: D21885261
fbshipit-source-id: 0352e6a830e6384e7ad747067f8bf8ad64ab7fa8
