[quant][graphmode][fx][refactor] Remove Quantizer class from convert (QuantizeHandler) (#59040)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59040
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: D28724870
fbshipit-source-id: c0f748711b825cd46bdfcc05c054c77a41e8207a
