UI: Option to automatically Hide UI when game launches

Quality of life feature. Removes the need to manually hide UI every time the game launches

src/Ryujinx/Utilities/Configuration/ConfigurationFileFormat.cs

@@ -351,6 +351,11 @@ namespace Ryujinx.Ava.Utilities.Configuration
         /// </summary>
         public bool StartFullscreen { get; set; }
 
+        /// <summary>
+        /// Start games with UI hidden
+        /// </summary>
+        public bool StartNoUI { get; set; }
+
         /// <summary>
         /// Show console window
         /// </summary>