Add qtensors in caffe2 protobuf argument (#18486)
Summary:
We are about to merge onnxifi quantization support soon. Before that, I would like to merge this diff seperately to make sure it doesnt break anything.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18486
Reviewed By: bddppq, houseroad
Differential Revision: D14626419
Pulled By: yinghai
fbshipit-source-id: 504c1eae60be1e629203267b59defb8b69d82c0a
