Move solution and projects to src

src/Ryujinx.Common/Configuration/BackendThreading.cs

@@ -0,0 +1,13 @@
+using Ryujinx.Common.Utilities;
+using System.Text.Json.Serialization;
+
+namespace Ryujinx.Common.Configuration
+{
+    [JsonConverter(typeof(TypedStringEnumConverter<BackendThreading>))]
+    public enum BackendThreading
+    {
+        Auto,
+        Off,
+        On
+    }
+}