Fix Qt6 deprecated APIs: QCheckBox::checkStateChanged, ExploratoryLocationViewshed

- Replace QCheckBox::stateChanged with checkStateChanged in:
  - lts_dialog.cpp
  - simple_esri_layer.cpp (2 occurrences)
  - layer_control_widget.cpp
  - symbol_dialog.cpp
- Replace LocationViewshed with ExploratoryLocationViewshed (ArcGIS SDK v300):
  - viewshed_analysis.h/.cpp
  - ViewshedLocation.h/.cpp
  - function_dialog.cpp (include)
- Update ViewshedLocation member variable type to ExploratoryLocationViewshed

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

qt6-after/qt6-migrated-legatus/Lts/Viewer/SituationMap/FunctionDialog/function_dialog.cpp

@@ -103,7 +103,7 @@
 #include <Raster.h>
 #include <RasterLayer.h>
 #include <AnalysisOverlay.h>
-#include <LocationViewshed.h>
+#include <ExploratoryLocationViewshed.h>
 
 // 3D
 #include <SimpleMarkerSceneSymbol.h>