Améliorer la saisie avec un éditeur WYSIWYG

[yaaax]

• Should handle existing markdown content
• The editor is configured with extensions:
  • all what's in StarterKit
  • code block lowlight
  • highlight
  • link
  • task
  • typography (with french double quotes)
• Some styles have been added to fit DSFR styling

Still work in progress, but a nice start!

To do:

• image uploading and placement inside editor
• menu buttons
• accessibility tests and improvements

[hissalht]

La coloration syntaxique de code n'est pas lisible en mode sombre.