UI: Switch from RGBA to BGRA swap chain format

DirectX team member claims BGRA might have flip optimization benefits.

UI/qt-display.cpp

@@ -86,7 +86,7 @@ void OBSQTDisplay::CreateDisplay()
 	gs_init_data info = {};
 	info.cx = size.width();
 	info.cy = size.height();
-	info.format = GS_RGBA;
+	info.format = GS_BGRA;
 	info.zsformat = GS_ZS_NONE;
 
 	QTToGSWindow(winId(), info.window);