Add workflows for creating and uploading docker images

[dennisvang]

We should add reusable workflows for building docker images and uploading them to docker hub.

These can be based on e.g. the current FDP workflow.

Also update to use latest actions and best practices, see e.g.:

• Introduction to GitHub Actions with Docker
• docker build and push action
• docker CI docs

Dependent projects:

• Separate test and deployment workflows, remove nexus deployment. FAIRDataPoint-client#162
• Separate github workflows for testing and deployment FAIRDataPoint#583
• https://github.com/FAIRDataTeam/FAIRDataStation
• https://github.com/FAIRDataTeam/TrainHandler-server
• https://github.com/FAIRDataTeam/TrainHandler-client
• ...