Update member pointer to Surface on LocationTextController on change

[dtedder]

When a user adds a new data source and uses it for elevation, there is no code to set the m_surface pointer on the LocationTextController tool. The current code only updates this property on GeoView changed which is not triggered by data getting added in this way. As a work around, the location changed event is currently querying to find the baseSurface every time. This should be updated by the SceneQuckView::layerViewStateChanged signal or by a custom signal that can be raised by the AddLocalDataController tool.