LibGL: Add Shader and Program class stubs

Userland/Libraries/LibGL/Shaders/Program.cpp

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2022, Stephan Unverwerth <s.unverwerth@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibGL/Shaders/Program.h>
+
+namespace GL {
+
+NonnullRefPtr<Program> Program::create()
+{
+    return adopt_ref(*new Program());
+}
+
+ErrorOr<void> Program::attach_shader(Shader&)
+{
+    TODO();
+    return {};
+}
+
+ErrorOr<void> Program::link()
+{
+    TODO();
+    return {};
+}
+
+}