Design scaffolding for extension deployment

We need to come up with the idea of how an extension author:
- Builds
- Packages
- Deploys

Standalone extensions and how we can make this as simple as possible through scaffolding, makefiles, dockerfiles with examples

Part of this ticket is to also document how an extension author can get started / use all of this.

Lets also document/devise how to create the `Secret` and the `NetworkPolicy` required cc @Boomatang

No specific files or tests are named. Start by reviewing how standalone extensions are currently built, packaged, and deployed, then identify the scaffolding, makefile, and dockerfile examples needed. Done means the workflow is documented, examples cover extension setup, and the required Secret and NetworkPolicy are documented.

Written by the indexing model from the issue text.