Support ConstantOfShape in Caffe2 ONNX Backend (#16108)
Summary:
This PR is the prerequisite to land https://github.com/pytorch/pytorch/pull/16095
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16108
Reviewed By: BIT-silence
Differential Revision: D13725722
Pulled By: houseroad
fbshipit-source-id: 28c0fb72f075cd04f9db44dfab0163844c20c620
