🎩 What? Why?

This PR adds multiple pages to a survey. Since a Survey has one Questionnaire, we use Questionnaires as steps, changing the kind of relation to a has_many. This change doesn't affect the DB.

Then we change the decidim-forms module to handle resources with a single questionnaire, or with multiple questionnaires. The number of questionnaires a resource has will be determined by the resource itself. Each questionnaire will be a different step.

This PR also changes the way to find out if a survey has been answered or not. We're currently relying on the questionnaire having answers, but this system would get costly with the refactors in this PR. Thus, we're creating a QuestionnaireAnswer model, which relates to a Questionnaire and a User and is used to detect whether the given Questionnaire has been answered by that user or not. QuestionnaireAnswer rows will only be created when the survey is sent. This change requires migrating the existing data.

This means that when a user moves from step 1 to step 2 of the survey, answers for step 1 will be persisted to the DB, but the QuestionnaireAnswer for that step will not be created until the survey is actually submitted.

This PR implies breaking changes:

• Surveys no longer respond to .questionnaire. They now respond to .questionnaires, and returns a list.
  • This affects the GraphQL API and the Surveys Importer

📌 Related Issues

• Fixes EPIC: Improve the Survey component #5728

📋 Subtasks

• Add CHANGELOG entry
• Add the QuestionnaireAnswer model and related migrations. Use that value to check whether the questionnaire has been answered or not.
• Let Survey have multiple questionnaires. No need for migration, only change the HasQuestionnaire concern. From now on, each questionnaire will be considered a different step/page of the same survey.
• Admin: List questionnaires when accessing the component
• Admin: allow users to create other pages for the same survey.
• Admin: allow admins to destroy questionnaires
• Admin: reorder steps (buttons just like questions)
• Public: show current step and total number of steps in the survey
• Public: Add navigation between steps
• Public: Only require TOS on last step
• Public: When changing steps, submit question answers
• Public: Create QuestionnaireAnswer on survey submission
• Public: Recover answers on previous steps
• Ensure multiple step submissions update answers instead of creating new ones
• Ensure all changes apply to meetings
• Implement Display number of responses in the survey administration panel #5729 if not done previously

📷 Screenshots (optional)