[ONNX] add test images to repo (#63717)
Summary:
This is better than the status quo:
* Test doesn't download files from the internet -> faster and more
reliable.
* Test doesn't leave the git working directory dirty.
Rather than using the original images, I've copied some images from
the pytorch/vision repo. This will keep the tests in the two repos
in sync, while avoiding adding new assets to the vision repo.
See https://github.com/pytorch/vision/pull/4176.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/63717
Reviewed By: janeyx99
Differential Revision: D30466016
Pulled By: malfet
fbshipit-source-id: 2c56d4c11b5c74db1764576bf1c95ce4ae714574
