cmake: migrate Qt5:: to Qt6:: in LtsWidgets CMakeLists_rc.txt

- Qt5::Core → Qt6::Core
- Qt5::Gui → Qt6::Gui
- Qt5::Widgets → Qt6::Widgets
- Qt5::Network → Qt6::Network
- Qt5::Svg → Qt6::Svg

Part of Qt5→Qt6 migration under C++17 constraint (RTI Connext DDS 7.7.0 blocker).

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

qt6-after/qt6-migrated-legatus/Lts/Common/LtsWidgets/CMakeLists_rc.txt

@@ -153,8 +153,8 @@ NGL_TARGET_INCLUDE_DIRECTORIES(LtsWidgets
 
 NGL_TARGET_LINK_LIBRARIES(LtsWidgets
   PRIVATE
-    Qt5::Network # for QHostInfo - for portability
-    Qt5::Svg
+    Qt6::Network # for QHostInfo - for portability
+    Qt6::Svg
     ngltools
     ngltranslator
     TabBarTabStyle
@@ -162,9 +162,9 @@ NGL_TARGET_LINK_LIBRARIES(LtsWidgets
     LtsUtilsSettings
   PUBLIC
     LtsUtilsCore
-    Qt5::Core
-    Qt5::Widgets
-    Qt5::Gui
+    Qt6::Core
+    Qt6::Widgets
+    Qt6::Gui
 )
 
 NGL_INSTALL_TARGET(LtsWidgets)