Demo - Proxying Cloud Kafka Provider(s)

[gracegrimwood]

The discussion in kroxylicious/kroxylicious#1650 has revealed a bit of a gap in our docs/quickstarts/demos where we don't state clearly or give clear examples of how to use Kroxylicious to proxy a cloud Kafka provider like Redpanda or Confluent, especially in regards to configuring TLS according to the cloud service providers' requirements.

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This issue makes me wonder if the documentation needs to be make it clearer that when used with TLS, the TLS is terminated at the proxy's downstream side and a new TLS connection is established between the upstream side and the cluster.

Originally posted by @k-wall in kroxylicious/kroxylicious#1650 (comment)

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Using Kroxylicious with a cloud Kafka provider will be a common use case for many users, so we should address this gap. This issue is about creating a demo and possibly a corresponding blog post, if that's where we decide the demo should go. Issues about addressing this in the Kroxylicious docs should be raised against the main kroxylicious/kroxylicious repository because the sources for the docs live there.

Once the operator is stable, we should create a demo and corresponding example configuration files for users to quickly get started with Kroxylicious and their cloud Kafka provider of choice. This could be done as a blog post (which is what we've done for demos in the past), or we could add it to the quickstarts, or we could even make a new page specifically for demos of Kroxylicious.

We will also need to decide which cloud Kafka provider(s) we want to make a demo for.