LibGL: Add Shader and Program class stubs

Userland/Libraries/LibGL/Shaders/Program.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2022, Stephan Unverwerth <s.unverwerth@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/NonnullRefPtr.h>
+#include <AK/RefCounted.h>
+#include <AK/Vector.h>
+#include <LibGL/Shaders/Shader.h>
+
+namespace GL {
+
+class Program final : public RefCounted<Program> {
+public:
+    static NonnullRefPtr<Program> create();
+
+    ErrorOr<void> attach_shader(Shader&);
+    ErrorOr<void> link();
+
+private:
+    Vector<NonnullRefPtr<Shader>> m_vertex_shaders;
+    Vector<NonnullRefPtr<Shader>> m_fragment_shaders;
+};
+
+}