[quant][graphmode][fx][refactor] Remove Quantizer class from quantize_node (#59039)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59039
To remove Quantizer class and split prepare and convert functions to different files
Test Plan:
python test/test_quantization.py TestQuantizeFx
python test/test_quantization.py TestQuantizeFxOps
Imported from OSS
Reviewed By: vkuzo
Differential Revision: D28724874
fbshipit-source-id: bd984716b2da1d6879c3e92fa827574783a41567
