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/EvalApps/Viewshed3D/ViewshedLocation.cpp

@@ -26,7 +26,7 @@
 #include "ArcGISTiledElevationSource.h"
 #include "Scene.h"
 #include "SceneGraphicsView.h"
-#include "LocationViewshed.h"
+#include "ExploratoryLocationViewshed.h"
 #include "Camera.h"
 #include "Point.h"
 #include "AnalysisOverlay.h"
@@ -139,7 +139,7 @@ void ViewshedLocation::createViewshed(double x, double y)
   for (int i = 0; i < 3; ++i)
   {
     double heading = i * 120.0;
-    m_locationViewshed[i] = new LocationViewshed(pt
+    m_locationViewshed[i] = new ExploratoryLocationViewshed(pt
       , heading
       , 90.0   // pitch
       , 120.0  // horizontalAngle