Automate as much things as possible

[szaimen]

When looking at the template #180 there are still a few things that need to be done manually. In best case only the three steps below should be required which should automate the manual steps as far as possible.

Basically should cover only three manual triggers:

1. auto build and publish to develop channel (with new version; smoke test afterwards)
2. promote to beta channel
3. promote to latest incl. project management

All manual steps should ideally be part of the workflow...

[szaimen]

https://github.com/nextcloud-gmbh/server/issues/255#issuecomment-1217936394