power: Re-introduce custom charging sounds

 * Mostly inspired by old implementation (see commit 72fe3994),
   but refactored to use most of the AOSP code.

 * Also adapted to the wireless charging feature introduced in P.

 Also include:

   power: Respect global vibration setting for charging sounds

    * Don't vibrate when in silent mode

   Change-Id: Ife14105e74a28856d74a4c153637344124686e1b

Change-Id: I5f6589002db51fe03ec2cf7bb33ed0e63948c55a