Set up continuous integration for OpenXLA Nvgpu project

[ezhulenev]

We need a CI that runs all tests + presubmit checks, etc... all the goodies we have in IREE core.

[stellaraccident]

@GMNGeoffrey would be useful to whiteboard some of what is needed here. @frgossen is open to do the work but would be useful to light the path...

[frgossen]

Thanks Geoffrey for providing an overview (offline). I will get resnet running end to end and focus on the CI after that

[julianwa]

Thanks, @frgossen! Not sure if Geoffrey covered benchmarking, but we should be reasonably well prepared to hook that up after CI is in place. You can connect with @mariecwhite and @pzread on this when ready.