UI: Rename visual update callback variable

Having both a "callback" and "cb" doesn't make sense. One is
specifically for visual updates only, the other is for actual updates,
so use an appropriate name for both

UI/properties-view.hpp

@@ -102,7 +102,7 @@ private:
 	std::string type;
 	PropertiesReloadCallback reloadCallback;
 	PropertiesUpdateCallback callback = nullptr;
-	PropertiesVisualUpdateCb cb = nullptr;
+	PropertiesVisualUpdateCb visUpdateCb = nullptr;
 	int minSize;
 	std::vector<std::unique_ptr<WidgetInfo>> children;
 	std::string lastFocused;