feat: Add collaborative_texts and elections

[AyakorK]

🎩 Description

Addition of decidim_collaborative_texts and decidim_elections to decidim-app 0.31

Testing

DECIDIM ELECTIONS

• Connect as an administrator
• Go to back-office
• Go to a participatory process
• Go to "elections" or create a new component
• Create a new election or multiple elections with multiple settings
• Make sure you can create it easily without any error
• Open one or more elections
• Try to vote on them
• Make sure you can make the entire process of voting
• Try to close an election in the back-office

DECIDIM COLLABORATIVE TEXTS

• Connect as an administrator
• Go to back-office
• Access a participatory process
• Go to "Collaborative texts" or create a new component
• Create a new collaborative text with mutliple paragraphs to make sure you can edit each one of them independantly
• Publish it and allow suggestions in the options
• Access front office with an other user account (ex : user@example.org)
• Try to submit some suggestions as a user
• Disconnect and log again as an administrator
• Make sure you can see each one of the suggestion you made as a user
• Try to accept some of them and ignore others
• Submit the changes and make sure the text is edited correctly and that suggestions you didn't accept were dropped

📌 Related Issues

Link your PR to an issue

• Fixes https://github.com/orgs/OpenSourcePolitics/projects/26/views/1?pane=issue&itemId=158409462&issue=OpenSourcePolitics%7Cintern-tasks%7C373

Tasks

• Add missing locales
• Add gems
• Add db migrations
• Update schema.rb

[BarbaraOliveira13]

LGTM 🎉