Improve the use of docker

[jdkandersson]

There are some opportunities to improve the use of docker by making an image available rather than needing to build every time.

[merkata]

Can you elaborate more please? Sounds good and it will be helpful to have more details.

[jdkandersson]

The action currently build the docker image on every run which takes about a minute or so. This issue would change that to be done once and uploaded to some image repository so that the image can just be downloaded and run rather than having to be built every time.

This will require changes to the way the workflow is implemented because a release has to be accompanies by a docker image for that release. We will also need to keep an image targeting the main branch up to date so that anyone targeting the default branch are also able to make use of the image. The e2e tests will also need to be changed so that they build and run the latest image on a given branch.