WindowServer+Taskbar: Animate window frames on minimize/unminimize

We now show a quick window outline animation when going in/out of
minimized state. It's a simple 10 frame animation at 60fps, just to
give a visual cue of what's happening with the window.

The Taskbar sends over the corresponding button rect for each window
to the WindowServer using a new WM_SetWindowTaskbarRect message.

Note that when unminimizing, we still *show* the window right away,
and don't hold off until the animation has finished. This avoids
making the desktop feel slow/sluggish. :^)

Applications/Taskbar/TaskbarButton.h

@@ -11,6 +11,7 @@ public:
 
 private:
     virtual void context_menu_event(GContextMenuEvent&) override;
+    virtual void resize_event(GResizeEvent&) override;
 
     WindowIdentifier m_identifier;
 };