CI: add job to build the docker image

This defines a template for building docker images as well as a
job to build the fedora image thats mean to replace the one
that's currently used.

Close #381
2 jobs for alatiera/docker-images in 6 minutes and 35 seconds (queued for 1 second)
latest
Status Job ID Name Coverage
  Docker Image
passed #144802
docker fedora amd64

00:04:30

 
  Build
passed #144803
build-mutter

00:02:05