Move the various room models into RoomManager

Move the various room models into RoomManager. This means the same room models are always used and is a base from which further logic can be moved from QML to cpp.

src/models/roomtreemodel.h

@@ -82,7 +82,7 @@ Q_SIGNALS:
     void connectionChanged();
 
 private:
-    QPointer<NeoChatConnection> m_connection = nullptr;
+    QPointer<NeoChatConnection> m_connection;
     QMap<NeoChatRoomType::Types, QList<QPointer<NeoChatRoom>>> m_rooms;
 
     void initializeCategories();