[quant][pt2e] Add support for SharedQuantizationSpec (#102184)
Summary:
This PR adds support for SharedQuantizationSpec, it's used to express the sharing between
two Tensors in the prepared graph, the Tensor will either be input of some node (expressed as a Tuple of fx nodes) or
output of some node (expressed as an fx Node)
Test Plan:
```
buck2 test mode/opt caffe2/test:quantization_pt2e -- 'caffe2/test:quantization_pt2e'
buck2 test mode/opt caffe2/test:quantization_pt2e -- --exact 'caffe2/test:quantization_pt2e - test_resnet18_with_quantizer_api (quantization.pt2e.test_quantize_pt2e.TestQuantizePT2EModels)'
```
Differential Revision: D46043026
Pull Request resolved: https://github.com/pytorch/pytorch/pull/102184
Approved by: https://github.com/kimishpatel, https://github.com/leslie-fang-intel
