Optimize processing speed by only processing tiles with GHSL built area or buildings
The Finalizer processes all level-18 tiles of a country. In many countries, only a small fraction of these tiles contain either GHSL built area or buildings. Because this information is given, it should be used to restrict the set of tiles to be processed to the ones containing either GHSL built area or buildings and skip all tiles with no information as the processing of these empty tiles will not yield any results.