Add BUILD_RTI conditionals for RTI/DDS dependent libraries

Systematic fix for BUILD_RTI conditional compilation:
- Lts/Common: Wrap all DDS-dependent libraries in IF(BUILD_RTI)
  - LtsAppManager, LtsCoordTrans, LtsCoordinate, LtsLogin
  - LtsMultiMonitor, LtsPluginManager, LtsPrinting
  - LtsProjectionWorkstation, LtsScriptTimeline, LtsSession
  - LtsTimelineClassic, LtsUtilsCore, LtsUtilsGui, LtsUtilsGuiDds
- Lts/DDS: Add BUILD_RTI guards to Core, DDSConnector, DdsUnitTests, FTC, FTS
- Lts/Plugins: Add BUILD_RTI guards to FilterManagement, OperatorManagement, SituationReplayManagement
- Lts/Proxies: Add BUILD_RTI guards to Buildings, CombatNetRadio, ComponentMonitor, GuezNasat, TrainingAreaBase, TrainingAreaBaseOC
- Lts/Services: Add BUILD_RTI guards to all 30+ service modules
- Z/nglwidgets: Add BUILD_RTI guards, fix Poppler Qt6 headers

Qt6 compatibility fixes:
- LtsCoordTrans: QOverload signal signature, QChar constructor
- LtsMultiMonitor: setMargin→setContentsMargins, remove deprecated HighQualityAntialiasing
- nglwidgets: Poppler Qt5→Qt6 header migration
- Add FindPopplerQt6.cmake for Qt6 Poppler detection

Part of Qt5→Qt6 migration with RTI DDS support.

qt6-after/qt6-migrated-legatus/Lts/Common/LtsMultiMonitor/lts_screen_wide.cpp

@@ -32,7 +32,6 @@ LtsScreenWide::LtsScreenWide(const QRect &screenGeo, int screenId, bool debugMar
   auto *theLayout = new QHBoxLayout;
 
   theLayout->setContentsMargins(0, 0, 0, 0);
-  theLayout->setMargin(0);
   theLayout->setSpacing(0);
   theLayout->setStretch(0, 9999);