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/Services/ProjectDataManagement/CMakeLists.txt

@@ -45,6 +45,7 @@ NGL_TARGET_INCLUDE_DIRECTORIES(svcPdmCommon
     ${CMAKE_CURRENT_SOURCE_DIR}/../
     ${CMAKE_CURRENT_BINARY_DIR}/../
 )
+IF(BUILD_RTI)
 NGL_TARGET_LINK_LIBRARIES(svcPdmCommon
   PRIVATE
     RTI::nddscpp2
@@ -55,6 +56,7 @@ NGL_TARGET_LINK_LIBRARIES(svcPdmCommon
     LtsUtilsCore
     ngldb
 )
+ENDIF(BUILD_RTI)
 NGL_INSTALL_TARGET(svcPdmCommon)
 
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