[hlx init] remove completely or replace

[tripodsan]

hlx init doesn't really do much but copy some demo files. so it's not really a init, but rather a quickstart / demo and could be removed.

suggestion

• remove hlx init
• create hlx demo which will install a minimal demo; maybe with a --simple / --full switch.

instead of bundling the demo into helix-cli we could manage the demos independently on github. eg: helix-project/archetypes/simple, helix-project/archetypes/full. not sure about the git-repo to use and/or how versioning affects the demos, etc.

[trieloff]

I like the idea of just cloning an example repository. We could maintain a list of known example repositories, which would also encourage people to contribute their examples of Helix + <whatever pet peeve tech they'd like to show off>

Versioning could be handled by inspecting the package.json of the demo. If the @adobe/helix-cli version in the package.json is greater than the current version, we show a warning or error.