LibDraw: Introduce (formerly known as SharedGraphics.)

Instead of LibGUI and WindowServer building their own copies of the drawing
and graphics code, let's it in a separate LibDraw library.

This avoids building the code twice, and will encourage better separation
of concerns. :^)

Libraries/LibGUI/GButton.cpp

@@ -4,7 +4,7 @@
 #include <LibGUI/GActionGroup.h>
 #include <LibGUI/GButton.h>
 #include <LibGUI/GPainter.h>
-#include <SharedGraphics/StylePainter.h>
+#include <LibDraw/StylePainter.h>
 
 GButton::GButton(GWidget* parent)
     : GAbstractButton(parent)