LibGUI: Add GMenu* and GApplication classes.

Author: https://github.com/awesomekling
Commit: 9483b39227

LibGUI/GMenuItem.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include <AK/AKString.h>
+
+class GMenuItem {
+public:
+    enum Type { Invalid, Text, Separator };
+
+    explicit GMenuItem(Type);
+    GMenuItem(unsigned identifier, const String& text);
+    ~GMenuItem();
+
+    Type type() const { return m_type; }
+    String text() const { return m_text; }
+    unsigned identifier() const { return m_identifier; }
+
+private:
+    Type m_type { Invalid };
+    unsigned m_identifier { 0 };
+    String m_text;
+};
+