Investigate Ginkgo-based E2E test fixture and add E2E tests

[jgwest]

At present, there are no E2E tests that we can run to verify the correctness rollouts-plugin-trafficrouter-openshift code. We should contribute tests to verify that functionality.

HOWEVER, at present, since these tests require OpenShift (require the Route CR), and there is no OpenShift integration in this repository, we will not be able to run these tests as part of GitHub Actions.

• We shouldn't/don't need to wait to have a solution to this. This is a case where the perfect is the enemy of the good.

When running these tests (for now), just assume there is already an OpenShift cluster defined in current kube context.

Issue Criteria:

• Ginkgo-based E2E tests
• Defined a fixture we can use to test this
  • The existing rollouts E2E tests can be used as inspiration, here, for example istio_test.go or canary_test.go.
• Define E2E tests that test Canary functionality with Routes.
• A Makefile target that runs the tests
  • For now, assume that Rollouts is already installed on the cluster, and rollouts-plugin-trafficrouter-openshift is already installed onto it.
• Tests running successfully on your local machine, when you are logged into an OpenShift

[jgwest]

External Red Hat Issue Tracker: https://issues.redhat.com/browse/GITOPS-4038