This creates a new go module for the e2e code and the kubetest2 skeleton.
Most of the kubetest2 code was copied from sigs.k8s.io/kubetest2/kubetest2-gke.
Currently only building (`make gcs-publish-ci`) is in place.
I used test-infra/scenarios/kubernetes_e2e.py as reference, removing env and make variables that are no longer needed.
Instructions:
```
cd tests/e2e
go install sigs.k8s.io/kubetest2
go install ./kubetest2-kops
kubetest2 kops -v 9 --build --stage-location=gs://foobar/ --kops-root=../../ # runs make gcs-publish-ci and exits
```
Peter Rifel