Support Exports to Multiple ONNX Opset (#19294)
Summary:
Support exporting multiple ONNX opsets (more specifically opset 10 for now), following the proposal in https://gist.github.com/spandantiwari/99700e60919c43bd167838038d20f353.
And add support for custom ops (merge with https://github.com/pytorch/pytorch/pull/18297).
This PR will be followed by another PR containing the changes related to testing the ops for different opsets.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/19294
Reviewed By: zrphercule
Differential Revision: D15043951
Pulled By: houseroad
fbshipit-source-id: d336fc35b8827145639137bc348ae07e3c14bb1c
