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.h

@@ -33,7 +33,7 @@ namespace Esri
 namespace ArcGISRuntime
 {
 class SceneGraphicsView;
-class LocationViewshed;
+class ExploratoryLocationViewshed;
 class AnalysisOverlay;
 }
 }
@@ -82,7 +82,7 @@ private:
   void createViewshed(double x, double y);
 
   Esri::ArcGISRuntime::SceneGraphicsView *m_sceneView = nullptr;
-  Esri::ArcGISRuntime::LocationViewshed  *m_locationViewshed[3] = { nullptr, nullptr, nullptr };
+  Esri::ArcGISRuntime::ExploratoryLocationViewshed  *m_locationViewshed[3] = { nullptr, nullptr, nullptr };
   Esri::ArcGISRuntime::AnalysisOverlay   *m_analysisOverlay = nullptr;
 
   bool m_viewshedVisible = true;