WindowServer: Start implementing a menu system.

I'm going with a global top-of-the-screen menu instead of per-window menus.
The basic idea is that menus will live in the WindowServer and clients can
create menus via WindowServer requests.

WindowServer/WSMenuItem.cpp

@@ -0,0 +1,16 @@
+#include "WSMenuItem.h"
+
+WSMenuItem::WSMenuItem(const String& text)
+    : m_type(Text)
+    , m_text(text)
+{
+}
+
+WSMenuItem::WSMenuItem(Type type)
+    : m_type(type)
+{
+}
+
+WSMenuItem::~WSMenuItem()
+{
+}