install onnxruntime tests on linux wheel for circle_ci

[r-zenine]

Hi,

This PR enable's onnx related tests for circleci for the linux_wheel pipelines. It is a first step at addressing this issue #1326

Thanks

[fmassa]

This generally looks good to me, thanks a lot @r-zenine!

I have one general comment: we currently don't run tests for wheels on CI, only on conda, so this PR wouldn't be enough to enable CI to use onnxruntime.

The current situation with testing in torchvision is a bit weird: we share the same scripts for building the binaries and for CI, but we only run a subset of those scripts in CI (namely, we only run conda tests for now).

This is something that I think should be improved / clarified (but is outside of the scope of this PR).

I'm ccing @seemethere for thoughts on how to best address this.

[r-zenine]

Hi @fmassa,

I spent some time trying to use pip inside the conda pipeline to install onnxruntime. I was hopping to find an elegant fix. But It does not look good so far.
We would need to run the test on wheel pipelines to have that.
What's preventing us from running tests on wheel pipelines ?

[fmassa]

Subsumed by #3144