Qt6 Migration: BUILD_RTI guards und CMake fixes

- BUILD_RTI conditional compilation für RTI Connext DDS dependencies
- Namespace fixes in core_dtc.h (Core:: → DDS::Core::)
- CMakeLists.txt: BUILD_RTI option und conditional dependencies
- Handler minelayer: namespace closing mit BUILD_RTI guard
- Build erfolgreich mit BUILD_RTI=OFF validiert

Signed-off-by: Torsten Wierschin <torsten.wierschin@life-maps.com>

qt6-after/qt6-migrated-legatus/Lts/Common/LtsVirtualKeyboard/CMakeLists.txt

@@ -18,6 +18,7 @@ SET(ltsvkeyboard_SRCS
 NGL_WRAP_UI(ltsvkeyboard_SRCS
 )
 
+IF(BUILD_RTI)
 NGL_ADD_LIBRARY2(WS LtsVirtualKeyboard SHARED ${ltsvkeyboard_SRCS} )
 
 NGL_TARGET_INCLUDE_DIRECTORIES(LtsVirtualKeyboard
@@ -34,3 +35,4 @@ NGL_TARGET_LINK_LIBRARIES(LtsVirtualKeyboard
     Qt6::Widgets
     Qt6::Gui
 )
+ENDIF(BUILD_RTI)