[CI] Add job for linting python files

Description

We have many Python scripts in our repository, but no automatic formatting checks in place as we have for C++. This MR adds a CI job that uses black to format all Python files. Note that the idea is not to fully customize the settings here; the only thing we adjust is the line length.

I also refactored the format jobs a bit to that we can apply them per language. The apply job applies all format diffs it finds.

Checklist

• Documentation reflects the changes made.
• Merge Request title is clear, concise, and suitable as a changelog entry. See our contributing docs

References

Closes #1353 (closed)