Fix hidden content in more information

[Stef-Rousset]

🎩 What? Why?

This PR adds an inert attribute on hidden content, and adds the toggle of the attribute when the content is displayed.
This PR is issued from the audit of Angers city (page 68) and corresponds to criterias 1.3.2 and 4.1.2 from WCAG.

📌 Related Issues

• Related to https://github.com/orgs/OpenSourcePolitics/projects/26/views/1?pane=issue&itemId=112587583&issue=OpenSourcePolitics%7Cintern-tasks%7C46

Testing

1. As an admin, go in the BO to the edit page of the process
2. In the description of the process, add 10 lines, and one or two links in it
3. In the FO, go to the process show page
4. Navigate with the keyboard, and see that the links in the hidden description are not accessible
5. Click on "More information"
6. Navigate with the keyboard, and see that the links are accessible

📷 Screenshots (optional)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions. @carolromero & @xabier feel free to chime in.