Support skipping some questions

## Problem

When I see a batch of questions, some might be irrelevant depending on the answers to previous ones, so I want to be able to partially answer the questionnaire. Like:
- q1: Use technology A?
- q2: If we use technology A, how do we do that?

Also, the "skip" button is misleading: I thought it would skip the specific question, but it skips the whole questionnaire and deletes all answers.

## Proposed solution

Make a skip button for the specific question.

## Alternatives considered

Make a submit button available always, even when answers are not fulfilled

Start at the questionnaire UI and reproduce the current skip-button behavior with dependent questions such as q1 and q2. Update the interaction so skipping affects only the current question, preserves existing answers, and allows the questionnaire to be partially answered.

Written by the indexing model from the issue text.