CI: added workflow for docker hub publishing TRG 4.05

[tom-rm-meyer-ISST]

Description

I added two workflows for github to publish images to docker hub. There is one workflow for the frontend and one for the backend that will be pulled automatically.
Uses, same as the example, following actions:

• build-and-push
• Dockerhub description update using README.md

This should trigger automatic builds with labels for nearly all git refs that are merged on main, except for the PR.

Pre-review checks

Please ensure to do as many of the following checks as possible, before asking for committer review:

• DEPENDENCIES are up-to-date. Dash license tool. Committers can open IP issues for restricted libs.
• Copyright and license header are present on all affected files

[mhellmeier]

LGTM, since the failed quality check pipeline relates to an upstream bug.