System UI for auto.

This change adds in the beginnings of System UI for
the automotive use case. We extend the Phone status
and navigation bar and override the parts which are
customized for auto.

The navigation bar itself is built from a resource
array specified in car_arrays.xml to allow of ease
of customization of the shortcuts that are in the
navigation bar.

Bug: 26301185
Change-Id: I780a2ef9dd5ae2a4be9355b5874d08f521a86fa7