Add script to run Rollouts tests against gitops-operator repo

[jgwest]

What type of PR is this?

/kind enhancement

What does this PR do / why we need it:

This PR adds a new shell script which can be run to verify the Argo Rollouts functionality within gitops-operator.

• It runs the (cluster-scoped) E2E tests of the Argo Rollouts operator
• It runs the upstream E2E tests from the argo-rollouts repo

This PR only adds the scripts to the repo, so they can be called manually. We can add integration to CI in a separate PR.

Have you updated the necessary documentation?

• [ ] Documentation update is required by this PR.
• [ ] Documentation has been updated.

[openshift-ci[bot]]

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[chetan-rns]

/test v4.12-kuttl-sequential

[jgwest]

Thanks @chetan-rns!