[quant][graphmode] FP16 quant support - Operator Fusion (#40710)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/40710
Test Plan:
python test/test_quantization.py
Imported from OSS
Differential Revision: D22335975
fbshipit-source-id: 5c176bb6b9c300e1beb83df972149dd5a400b854
