[quant][graph] Add support for FP16 dynamic quant (#42222)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42222
This change adds the necessary passes to perform FP16 dynamic quantization.
We skip inserting observers for activations based on the dtype (torch.float16) and only insert the Fp16Observer for weights
Test Plan:
python test/test_quantization.py TestQuantizeJitOps
Imported from OSS
Reviewed By: jerryzh168
Differential Revision: D22849220
fbshipit-source-id: 2c53594ecd2485e9e3dd0b380eceaf7c5ab5fc50
