SystemUI: Allow to enable Lockscreen Media Art

This is a squash of the following commits:

Author: beanstown106 <nbenis106@gmail.com>
Date:   Fri Oct 23 21:07:35 2015 -0400

    SystemUI: Allow to enable Lockscreen Media Art

    Change-Id: Id93e115649df5d6dc680101a8c852644b217c28a

Author: Ezio Lacandia Bijelkic <brabus84@gmail.com>
Date:   Fri Nov 20 00:41:04 2020 +0200

    SystemUI: Hide lockscreen media art if media is not playing

    it's annoying to get the artwork even if the notification gets
    swiped out and media is paused, because the media session is still alive

    Change-Id: Ie65932127e47c463ef9a8b763298fc4dae20f8ae

Change-Id: Idd3033b52b4aa1cf07eb694ea0c9c1c934248f7c