Replace Qt5:: with Qt6:: in 26 CMakeLists.txt files

Qt6 migration: Update all target_link_libraries to use Qt6::Core, Qt6::Widgets,
Qt6::Network, Qt6::Svg, Qt6::Xml, Qt6::Concurrent, Qt6::PrintSupport, Qt6::Sql,
Qt6::Test, Qt6::WebSockets, Qt6::SerialPort instead of Qt5:: equivalents.

Affected components:
- Lts/Common: LtsRestClient, LtsWidgets
- Lts/Application: THP, SitMapReplayTest
- Lts/Plugins: ParticipantManagement, ServiceManagement
- Lts/Services: VideoOverlayManagement
- Lts/Tools: 18 tool CMakeLists.txt files

Validated with BUILD_RTI=ON and BUILD_RTI=OFF - both builds successful.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

qt6-after/qt6-migrated-legatus/Lts/Tools/DBUpdate/CMakeLists.txt

@@ -294,8 +294,8 @@ NGL_WRAP_UI(SRCS ui/db_update.ui ui/show_history.ui)
 NGL_ADD_EXECUTABLE(SV dbUpdate ${SRCS})
 
 NGL_TARGET_LINK_LIBRARIES(dbUpdate
-  Qt5::Widgets
-  Qt5::Core
+  Qt6::Widgets
+  Qt6::Core
   nglapplication
   ngldb
   nglcoreapplication