GODT-1984: Handle permanent message deletion

Only delete messages when unlabeled from trash/spam if they only exists
in All Mail and (spam or trash).

This patch also ports delete_from_trash.feature and use status rather
than fetch to count messages in a mailboxes.

internal/user/events.go

@@ -289,7 +289,9 @@ func (user *User) handleMessageEvents(ctx context.Context, messageEvents []litea
 			}
 
 		case liteapi.EventDelete:
-			return ErrNotImplemented
+			if err := user.handleDeleteMessageEvent(ctx, event); err != nil {
+				return fmt.Errorf("failed to handle delete message event: %w", err)
+			}
 		}
 	}
 
@@ -331,6 +333,20 @@ func (user *User) handleUpdateMessageEvent(_ context.Context, event liteapi.Mess
 	}, user.updateChLock)
 }
 
+func (user *User) handleDeleteMessageEvent(_ context.Context, event liteapi.MessageEvent) error { //nolint:unparam
+	return safe.RLockRet(func() error {
+		for _, updateCh := range user.updateCh {
+			update := imap.NewMessagesDeleted(
+				imap.MessageID(event.ID),
+			)
+
+			updateCh.Enqueue(update)
+		}
+
+		return nil
+	}, user.updateChLock)
+}
+
 func getMailboxName(label liteapi.Label) []string {
 	var name []string