Building release artifacts

[lars-t-hansen]

Now that we have a documented uplift/backport and release procedure (testing now with v0.12.1) we might want to think about whether we want to automate the building of release artifacts, ie executables. At the moment, everyone is running Linux on x86_64 so this does not have to be hard. (UiO have some HPC systems that I think should have Sonar that are running ARM64, and of course there's A2, but that's down the road.) Mostly we need some kind of workflow for this that's triggered when we push the Make-a-release button in the Github API?