Migrates remaining include, viewer and DDS headers to rtiddsgen API

Converts accessor calls to plain member access and fixes SituationMap CMake.

qt6-after/qt6-migrated-legatus/include/Viewer/SituationMap/ElevationMap/elevation_map_manager.h

@@ -25,7 +25,9 @@ using LOSVector = std::vector<double>;
 namespace SituationMap
 {
 
-class ElevationMapManager final : public QObject
+// The NGL build uses -fvisibility=hidden; LtsElevation links this class
+// across the shared library boundary, so it needs default visibility.
+class __attribute__((visibility("default"))) ElevationMapManager final : public QObject
 {
     Q_OBJECT