[ONNX] Added support for constant folding onnx::Add and onnx::Sub (#35869)
Summary:
Added support for constant folding onnx::Add and onnx::Sub
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35869
Reviewed By: hl475
Differential Revision: D20865640
Pulled By: houseroad
fbshipit-source-id: 2b8c1cc196959b5b5b9ce018dbdcb74d59a92d9f