Remove use of reflection on GAL multithreading (#4287)

* Introduce new IGALCommand<T> interface and use it

* Remove use of reflection on GAL multithreading

* Unmanaged constraint

Ryujinx.Graphics.GAL/Multithreading/Commands/IGALCommand.cs

@@ -4,4 +4,9 @@
     {
         CommandType CommandType { get; }
     }
+
+    interface IGALCommand<T> where T : IGALCommand
+    {
+        abstract static void Run(ref T command, ThreadedRenderer threaded, IRenderer renderer);
+    }
 }