Lts/Viewer: Migrate CMakeLists.txt to Qt6 and add missing submodules

- Updated all CMakeLists.txt files to use Qt6:: libraries
- Added LtsFileDialog submodule (copied from qt5-before)
- Added LtsReportDisplay submodule (copied from qt5-before)
- Enabled both submodules in main Viewer CMakeLists.txt
- Qt5::Core/Widgets → Qt6::Core/Widgets in all Viewer modules

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

qt6-after/qt6-migrated-legatus/Lts/Viewer/SituationMap/SymbologyXML/Gui/CMakeLists.txt

@@ -30,11 +30,11 @@ NGL_TARGET_LINK_LIBRARIES(advancedSymbologyXML_Gui
     situationMapGeometryModel
     advancedSymbology
     NGLLogger
-    Qt5::Gui
+    Qt6::Gui
   PUBLIC
     LtsWidgets
     NGLLogger
-    Qt5::Core
+    Qt6::Core
 )
 
 NGL_INSTALL_TARGET(advancedSymbologyXML_Gui)