Squash of SystemUI: Show bluetooth battery level

Author: LuK1337 <priv.luk@gmail.com>
Date:   2018-10-31 16:31:19 +0100
    SystemUI: Show bluetooth battery level when available

    * Somewhat inspired by change committed by Gavin Ni <gisngy@gmail.com>
      back in cm-13.0 days (see commit 88e7a6c7). Since then completely
      rewritten using BluetoothDevice API introduced in Oreo, with new
      drawables meant to be used with 0-9 battery level range.

    Change-Id: I6179bfd41e033591534e8cf3c6adc98ce715a13d

Author: Luca Stefani <luca.stefani.ge1@gmail.com>
Date:   2021-08-23 10:11:54 +0200
    fixup! SystemUI: Show bluetooth battery level when available

    The current update method is triggered in 2 cases:
      the SystemUI bluetooth controller changes device state
      the battery level changed intent is sent

    Sadly the current SysUI controller doesn't handle battery level
    changes, and is instead triggered in a few other cases ( ex audio
    state changed ).
    And since we use the data from SysUI controller for battery level
    from changes in the global bt controller we may have 2 different
    set of devices to work on. This could ( and does ) trigger
    race conditions.

    Instead add support battery level state changes within the SystemUI
    controller to work on the same data set.

    Change-Id: Ib57096fc2ebe151ac3860277a4db2319f230b514

Change-Id: I34344907711b7b9fc4c1d15d4516bd53bf30ebb2