feat: refactor email tagging system to use labels instead of colors

- Updated EmailContextMenu to replace color tag functionality with label tags.
- Modified EmailListItem to display label badges for emails based on keywords.
- Enhanced EmailViewer to include a tag picker for emails.
- Adjusted ThreadListItem to show label badges for email subjects.
- Added tests for email list item and keyword settings to ensure proper functionality of the new tagging system.
- Updated localization files to reflect changes from color tags to labels in multiple languages.

locales/fr/common.json

@@ -155,9 +155,10 @@
     "back_to_list": "Retour à la liste",
     "message_details": "Détails du message",
     "more_reply_options": "Plus d'options de réponse",
-    "set_color": "Définir la couleur",
+    "set_color": "Définir l'étiquette",
+    "tag": "Étiquette",
     "more_actions": "Plus d'actions",
-    "remove_color": "Retirer la couleur",
+    "remove_color": "Retirer l'étiquette",
     "more_count": "+{count} de plus",
     "characters_count": "{count} caractères",
     "quick_reply_placeholder": "Écrivez une réponse rapide...",
@@ -929,8 +930,8 @@
     "delete": "Supprimer",
     "mark_as_spam": "Signaler comme spam",
     "not_spam": "Pas un spam",
-    "color_tag": "Étiquette de couleur",
-    "remove_color": "Supprimer la couleur",
+    "color_tag": "Étiquette",
+    "remove_color": "Supprimer l'étiquette",
     "items_selected": "{count} emails sélectionnés"
   },
   "shortcuts": {