feat: add linter for version control

[eric-thelin]

When running our automated checks we want to ensure that everything is
version controlled. Otherwise there is a risk that we get false results,
i.e. false positives or false negatives.

This is essentially a port of the corresponding check we had in the
code_quality.sh script.

Checklist

• Changes are limited to a single goal (avoid scope creep)
• I confirm that I have read any Contribution and Development guidelines (CONTRIBUTING and DEVELOPMENT) and are following their suggestions.
• I confirm that I wrote and/or have the right to submit the contents of my Pull Request, by agreeing to the Developer Certificate of Origin, (adding a 'sign-off' to my commits).