Migrate docker image building to Github Actions

[KristianLyng]

Migrate docker image building to Github Actions

[sklirg]

I accidentally pushed some commits to primary in this repo instead of primary in my fork, but you can verify my fork for the work done and the added action.

Steps maybe needed by you (@KristianLyng) with admin perms:

• Go to here: https://github.com/telenornms/skogul/pkgs/container/skogul
  • Click Package Settings
  • Verify that "Actions" has write permissions0 (This might have to be done through the organization page somehow ("telenornms"), as you can see from the attached screenshot0 I did it on my "personal profile")

I took the liberty to test a build on tag release in this repo as well, which ended up with:

Error: buildx failed with: ERROR: denied: permission_denied: write_package

• https://github.com/telenornms/skogul/actions/runs/3472955590/jobs/5804425446

[sklirg]

Fixed!