base

Eliminate hw.keyboards system properties.

Stop using system properties to publish information about
the key character map path.  Instead, we can retrieve it
on demand by asking the window manager.

It was possible to exhaust the supply of system properties
when repeatedly adding and removing input devices.

Bug: 5532806
Change-Id: Idd361a24ad7db2edc185c8546db7fb05f9c28669