Minor preparations for question/questionnaire split

[Kakadus]

extracted some independent changes from #2513 for easier reviewability

1. pylint rule is covered in ruff and needed for out-of-line imports in temporary tool
2. question types helped me a lot to avoid question <-> questionassignment confusions
3. unrelated typo fix
4. fixed odd questionnaire type handling in text answer exporter (+ added type assertion) found while tracing question usage

[niklasmohrin]

Awesome, thank you!

[niklasmohrin]

Do you mind changing the title to something like "Minor preparations for question/questionnaire split", or anything else that summarizes the content instead of the act of creating the PR? I was slightly confused about what "independent questions" are when I saw the github notification :D