What would you like to be added

Deprecate direct playbook usage / kubespray vendoring.
Only support usage as a collection.

What's needed for this:

• Figuring out any things not working as a collection anymore and fix it
• Removing the top level playbooks which are just importing other playbook
• Move the CI

Why is this needed

Supporting both ways is complicated, since some stuff (notably related to plugins/module resolution) don't work exactly the same way).

For example custom filter plugins needs to be fully qualified in a collection, which does not work with the previous way (filter_plugins dir and unqualified name)