Support additional screen layouts.

Allows users to choose a single screen layout or a large screen layout.
Adds a configuration option to change the prominent screen.

src/citra_qt/bootmanager.cpp

@@ -161,9 +161,7 @@ void GRenderWindow::OnFramebufferSizeChanged() {
     qreal pixelRatio = windowPixelRatio();
     unsigned width = child->QPaintDevice::width() * pixelRatio;
     unsigned height = child->QPaintDevice::height() * pixelRatio;
-
-    NotifyFramebufferLayoutChanged(
-        EmuWindow::FramebufferLayout::DefaultScreenLayout(width, height));
+    UpdateCurrentFramebufferLayout(width, height);
 }
 
 void GRenderWindow::BackupGeometry() {