Add mail categories support

Wino.Core.Domain/Enums/MailOperation.cs

@@ -13,6 +13,7 @@ public enum MailSynchronizerOperation
     AlwaysMoveTo,
     MoveToFocused,
     Archive,
+    UpdateCategories,
 }
 
 public enum FolderSynchronizerOperation
@@ -35,6 +36,13 @@ public enum CalendarSynchronizerOperation
     TentativeEvent,
 }
 
+public enum CategorySynchronizerOperation
+{
+    CreateCategory,
+    UpdateCategory,
+    DeleteCategory,
+}
+
 // UI requests
 public enum MailOperation
 {