Currently, no tests exist for kcctl at all. We should add tests for the different commands, so to avoid regressions down the road. As part of this task, we need to

• Understand how PicoCLI applications are tested; is their any guidance in their docs?
• Set up the infrastructure for integration tests via Testcontainers; we'll need to start up ZooKeeper, Kafka, and Kafka Connect for testing kcctl; as inspiration or starting point, here's a Docker Compose file which shows the required components; as a test connector, the built-in file connector could probably be used