Fix BUILD_RTI=OFF build: Guard RTI-only DDS modules

- LtsUtilsSettings: Fix export header include path (angle brackets)
- LtsWidgets: Move LtsUtilsSettings to PUBLIC link libraries
- BatteryNotification: Remove unused QDesktopWidget include
- DDS/FTC: Wrap ddsftccore library in IF(BUILD_RTI) guards
- DDS/FTS: Remove ELSE block, wrap entire library in IF(BUILD_RTI)
- DDS/DTC: Wrap entire library definition in IF(BUILD_RTI)
- DDS/DTS: Wrap entire library definition in IF(BUILD_RTI)
- DDS/DDSConnector: Wrap entire library in IF(BUILD_RTI), remove ELSE
- DDS/Routing: Wrap entire library in IF(BUILD_RTI)

All RTI Connext DDS-specific libraries (ddscore, ddsQoS, ddsgen,
ddsdtc, ddsdts, ddsfts, ddsconnector, routing_plugin) are now
properly guarded so BUILD_RTI=OFF builds can succeed.

qt6-after/qt6-migrated-legatus/Lts/DDS/DTC/CMakeLists.txt

@@ -4,6 +4,8 @@
 # $Author$
 #
 
+IF(BUILD_RTI)
+
 ADD_LIBRARY(ddsdtc INTERFACE)
 TARGET_INCLUDE_DIRECTORIES(ddsdtc
   INTERFACE
@@ -21,3 +23,5 @@ SET(SRCS
   ${CMAKE_CURRENT_SOURCE_DIR}/generic_dtc_impl.h
 )
 TARGET_SOURCES(ddsdtc INTERFACE ${SRCS})
+
+ENDIF(BUILD_RTI)