Add CI workflow to test kor against Kubernetes

[stavmatityahu]

Is your feature request related to a problem? Please describe.

There’s currently no CI that tests kor against a live Kubernetes cluster.

Describe the solution you'd like

Add a GitHub Actions workflow that starts a KinD cluster, applies sample resources, and runs kor all.

Describe alternatives you've considered

Manual testing, but it doesn’t scale.

Additional context

I’m happy to open a PR with a first version of the workflow.