[quant][graphmode][fx] Merge quant_env and env (#59028)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/59028
Previously we have an env and a quant_env in convert, which is a bit confusing,
in this PR we merged them and have a Dict[str, Tuple[Node, torch.dtype]]
Test Plan:
python test/test_quantization.py TestQuantizeFx
python test/test_quantization.py TestQuantizeFxOps
Imported from OSS
Reviewed By: vkuzo
Differential Revision: D28724863
fbshipit-source-id: 722a682c70d300a6ccd2b988786a1ac2d45e880e
