Setup pre-commit code quality gate

A source code check should be implemented to analyze quality and complexity at the pre-commit stage. It should be integrated in the Gitlab CI with its own runner and write the results to an artifact.

Steps

• Initial commit with suggested hooks implemented run on entire code
• Assess revealed issues from report and fix them -> erroneous commits should not be blocked
• Merge clean branch to main -> erroneous commits should be blocked and checks should only run on changed files

This will use the pre-commit package.