Draft: Distribute CI files that includes from template, plus tests

Changing the suggested ci file to include from this repo rather than just distribute whole ci files.

Also, setting up some testing.

However, this needs:

• Add canvas api token to regler group as masked and protected variable (https://gitlab.control.lth.se/groups/regler/-/settings/ci_cd)
• Make this repo public to make it easier to include template
• Set up a test canvas course if there's not already one and add the course code to .gitlab-ci.yml.

Could you help me with those @albheim?