QT add Custom Layout Menu Option.

This add Custom Layout selector in Both Menu and Enhancment Setting. This will allow to use or change Custom Layout mode or by using toggle. Still No Overlay Editor, just manual edit box, and this Not saved or carried at per game settings

src/common/settings.h

@@ -42,6 +42,7 @@ enum class LayoutOption : u32 {
     SeparateWindows,
 #endif
     HybridScreen,
+    CustomLayout,
     // Similiar to default, but better for mobile devices in portrait mode. Top screen in clamped to
     // the top of the frame, and the bottom screen is enlarged to match the top screen.
     MobilePortrait,