Add support for input devices that have vibrators.

Added a getVibrator() method to InputDevice which returns a Vibrator
associated with that input device.  Its uses the same API as the
system vibrator which makes it easy for applications to be modified
to use one or the other.

Bug: 6334179
Change-Id: Ifc7f13dbcb778670f3f1c07ccc562334e6109d2e