Apply the new room creation design

[giomfo]

• Update the room creation screen according to the following design:
  
• Rename "Salon public" with "Salon forum"
• use the new icons
• The strings provided in the design have been replaced with the following ones:
  "Private room": "Salon privé",
  "Accessible to all users by invitation from an administrator.": "Accessible à tous les utilisateurs sur invitation d’un administrateur",
  "Private room opened to externals": "Salon privé ouvert aux externes",
  "Accessible to all users and to external guests by invitation of an administrator.": "Accessible à tous les utilisateurs et aux invités externes sur invitation d’un administrateur",
  "Forum room": "Salon forum",
  "Accessible to all users from the forum directory or from a shared link.": "Accessible à tous les utilisateurs à partir de la liste des forums ou d’un lien partagé",