Move over shared UI from AppWindow to Launcher

Currently AppWindow contains 2 different parts:
* Base code for all applications
* Launcher toolbar, menubar, statusbar and logic that is specific
  to switching between apps.

The latter is being moved over to Launcher, which is also
no longer inheriting from AppWindow, which is needed.

Change-Id: Ib5e93e2641062eb3027ccdd47e44083e2eda59d9