LibVirtGPU: Add a new GPU device that talks to our VirtIO-GPU driver

At this moment this only contains function stubs.

Userland/Libraries/LibVirtGPU/Shader.h

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2022, Stephan Unverwerth <s.unverwerth@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibGPU/Shader.h>
+
+namespace VirtGPU {
+
+class Shader final : public GPU::Shader {
+public:
+    Shader(void const* ownership_token);
+};
+
+}