Implement Caret and Focus Tracking for GNOME Shell

by Magdalen Berns for GNOME

To implement a caret and focus tracking device within GNOME Shell and allow the magnifier to use this device to display current keyboard focus. This work would contribute a focus and caret tracking "device" within GNOME Shell to the benefit of the GNOME community. The work also allows the magnifier to use this device in order to display current keyboard focus which enable users with low vision to use GNOME more easily.