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/GFilePicker.cpp

@@ -11,7 +11,7 @@
 #include <LibGUI/GSortingProxyModel.h>
 #include <LibGUI/GTextBox.h>
 #include <LibGUI/GToolBar.h>
-#include <SharedGraphics/PNGLoader.h>
+#include <LibDraw/PNGLoader.h>
 
 Optional<String> GFilePicker::get_open_filepath()
 {