SystemUI: Allow using tuner API for LineageSettings

Rebrand to Lineage and add support for custom string settings.
Based on a squash of the following changes:

Author: Steve Kondik <steve@cyngn.com>
Date:   Tue Sep 13 23:46:34 2016 -0700

    systemui: Allow using tuner API for CMSettings

     * Use the prefix "cm:" on the key supplied and it will redirect
       to CMSettings.

    Change-Id: Id4266a568deb8fb32857136990711b5d9d487721

Author: Zhao Wei Liew <zhaoweiliew@gmail.com>
Date:   Thu Oct 13 19:19:03 2016 +0800

    SystemUI: tuner: Allow Tuner API for System settings

    We'd like to modify some AOSP System settings as well.

    Change-Id: I4e2e7bf680f20bce9619ff2adf243d0f8f4a9906

Author: Bruno Martins <bgcngm@gmail.com>
Date:   Mon Sep 17 11:49:27 2018 +0100

    TunerServiceImpl: Add support for Lineage global settings

    Change-Id: I7f3a2e024286f2d7c49e173a7a0bb9a2f486c5d9

Change-Id: Ide9622ea4c7be371b83ff7ae9a73ce5565423af1