Add support for alpha to coverage dithering (#3069)

* Add support for alpha to coverage dithering

* Shader cache version bump

* Fix wrong alpha register

* Ensure support buffer is cleared

* New shader specialization based approach

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

@@ -0,0 +1,18 @@
+namespace Ryujinx.Graphics.GAL.Multithreading.Commands
+{
+    struct SetMultisampleStateCommand : IGALCommand
+    {
+        public CommandType CommandType => CommandType.SetMultisampleState;
+        private MultisampleDescriptor _multisample;
+
+        public void Set(MultisampleDescriptor multisample)
+        {
+            _multisample = multisample;
+        }
+
+        public static void Run(ref SetMultisampleStateCommand command, ThreadedRenderer threaded, IRenderer renderer)
+        {
+            renderer.Pipeline.SetMultisampleState(command._multisample);
+        }
+    }
+}