Enable 1-click remote dev environments for all hands-on labs with Gitpod or Codespaces

[chuck-confluent]

(Taken from confluentinc/kafka-tutorials#937 over at the Kafka Tutorials repo. The same reasoning applies.)

The current kafka tutorials user experience is sub optimal:

• User must install Docker, ccloud CLI, and sometimes other tools
• User must download several GB of docker images
• User must do things like exec into containers in order to use tools installed within

Ideally the user experience would be:

• Click a link to open a remote dev environment with all prerequisites baked in.
• Focus entirely on the learning objective

This more ideal user experience is possible with gitpod workspaces or GitHub Codespaces. In fact, I've already "gitpodified" a kafka tutorial here!

Enabling gitpod would require configuring a .gitpod.yml file in the repo root. Gitpod doesn't yet support multiple .gitpod.yml files, but as a workaround, we could use environment variables via URL (docs and example) to automatically change into the proper code directory on launch. This would mean we'd need one workspace to be able to run any tutorial which should be fine since everything is on docker. If something's not on docker, we could just install it to the workspace, or alias it with docker underneath (e.g. how the az CLI is aliased in the kafka docker playground project here)