Add option to change controller LED color (#572)

This allows the user to change the controller LED while using Ryujinx.
Useful for PS4 and PS5 controllers as an example.

You can also use a spectrum-cycling Rainbow color option, or turn the LED off for DualSense controllers.

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Co-authored-by: Evan Husted <greem@greemdev.net>

src/Ryujinx.Input/IGamepad.cs

@@ -65,6 +65,15 @@ namespace Ryujinx.Input
         /// <param name="configuration">The configuration of the gamepad</param>
         void SetConfiguration(InputConfig configuration);
 
+        /// <summary>
+        /// Set the LED on the gamepad to a given color.
+        /// </summary>
+        /// <remarks>Does nothing on a controller without LED functionality.</remarks>
+        /// <param name="packedRgb">The packed RGB integer.</param>
+        void SetLed(uint packedRgb);
+
+        public void ClearLed() => SetLed(0);
+
         /// <summary>
         /// Starts a rumble effect on the gamepad.
         /// </summary>