[quant][pt2e] Add observer_or_fake_quant_ctr to QuantizationSpec (#101920)
Summary:
This is the second refactor to align the annotation API with design,
next step is to change prepare_pt2e to consume QuantizationSpec object directly
Test Plan:
```
buck2 test mode/optcaffe2/test:quantization_pt2e -- --exact 'caffe2/test:quantization_pt2e - test_resnet18_with_quantizer_api (quantization.pt2e.test_quantize_pt2e.TestQuantizePT2EModels)'
```
Reviewed By: kimishpatel
Differential Revision: D45927416
Pull Request resolved: https://github.com/pytorch/pytorch/pull/101920
Approved by: https://github.com/andrewor14
