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.

---------

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

src/Ryujinx.Input.SDL2/SDL2GamepadDriver.cs

@@ -173,5 +173,16 @@ namespace Ryujinx.Input.SDL2
 
             return new SDL2Gamepad(gamepadHandle, id);
         }
+
+        public IEnumerable<IGamepad> GetGamepads()
+        {
+            lock (_gamepadsIds)
+            {
+                foreach (string gamepadId in _gamepadsIds)
+                {
+                    yield return GetGamepad(gamepadId);
+                }
+            }
+        }
     }
 }