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/external/include/KF6/KTextTemplate/ktexttemplate_version.h

@@ -0,0 +1,12 @@
+// This file was generated by ecm_setup_version(): DO NOT EDIT!
+
+#ifndef KTEXTTEMPLATE_VERSION_H
+#define KTEXTTEMPLATE_VERSION_H
+
+#define KTEXTTEMPLATE_VERSION_STRING "6.0.0"
+#define KTEXTTEMPLATE_VERSION_MAJOR 6
+#define KTEXTTEMPLATE_VERSION_MINOR 0
+#define KTEXTTEMPLATE_VERSION_PATCH 0
+#define KTEXTTEMPLATE_VERSION ((6<<16)|(0<<8)|(0))
+
+#endif