UI: Add the ability to change a DualSense/DualShock 4's LED color.

Not functional yet. This is the UI & persistence side of #572.

src/Ryujinx.Common/Configuration/Hid/Controller/GenericControllerInputConfig.cs

@@ -78,5 +78,10 @@ namespace Ryujinx.Common.Configuration.Hid.Controller
         /// Controller Rumble Settings
         /// </summary>
         public RumbleConfigController Rumble { get; set; }
+        
+        /// <summary>
+        /// Controller LED Settings
+        /// </summary>
+        public LedConfigController Led { get; set; }
     }
 }