[quant][fx][graphmode] Remove Quantizer class (#59606)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/59606
Test Plan:
python test/test_quantization.py TestQuantizeFx
Imported from OSS
Reviewed By: vkuzo
Differential Revision: D28951432
fbshipit-source-id: 3301f7200a4c7166673c27f9ac7ff559f1e6935d
