Refactors selection handling for improved code clarity

Modernize the interface to selection system. Create and return data instead of populating incoming parameters.

ApplicationLibCode/Application/RiaGuiApplication.cpp

@@ -1520,10 +1520,7 @@ void RiaGuiApplication::applyGuiPreferences( const RiaPreferences*
             }
         }
 
-        std::vector<caf::PdmUiItem*> uiEditorsToUpdate;
-        caf::SelectionManager::instance()->selectedItems( uiEditorsToUpdate );
-
-        for ( caf::PdmUiItem* uiItem : uiEditorsToUpdate )
+        for ( caf::PdmUiItem* uiItem : caf::SelectionManager::instance()->selectedItems() )
         {
             uiItem->updateConnectedEditors();
         }