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. :^)

Applications/QuickShow/main.cpp

@@ -6,7 +6,7 @@
 #include <LibGUI/GMenu.h>
 #include <LibGUI/GMenuBar.h>
 #include <LibGUI/GWindow.h>
-#include <SharedGraphics/PNGLoader.h>
+#include <LibDraw/PNGLoader.h>
 #include <stdio.h>
 
 int main(int argc, char** argv)