misc: Move configuration management to the Ryujinx project (#2269)

* Decouple configuration from Ryujinx.HLE and Ryujinx.Input

* Move Configuration to the Ryujinx project

Ryujinx/Configuration/AudioBackend.cs

@@ -0,0 +1,10 @@
+namespace Ryujinx.Configuration
+{
+    public enum AudioBackend
+    {
+        Dummy,
+        OpenAl,
+        SoundIo,
+        SDL2
+    }
+}