[FEATURE] Add push to GitHub docker registry for image builds
This change adds for all defined image builds the push for all tags additionally to the GitHub Packages Docker Registry.
One the one hand extension and projects using GitHub actions along with the core images can now benefit from pulling images from internal GitHub infrastructure instead from docker hub.
This further prepares for switching from docker hub to an alternative docker image registry, due docker announcent removal for free team accounts for open source projects.