Settings: Add setup UI for minimum delay between an app's notification sounds

Author: LuK1337 <priv.luk@gmail.com>
Date:   Tue Jul 23 20:28:56 2019 +0200

    Settings: Preserve sound timeout pref when showing legacy notification settings

    * Fixes : https://gitlab.com/LineageOS/issues/android/issues/936
              https://gitlab.com/LineageOS/issues/android/issues/939

    Change-Id: I61da5790fd09f6340c6fdbe89378114cd1e0dc5b

Author: Luk1337 <priv.luk@gmail.com>
Date:   Tue Aug 27 17:35:07 2019 +0800

    Settings: Remove sound timeout preference from channel_settings PreferenceScreen

    * Fixes: https://gitlab.com/LineageOS/issues/android/issues/1098

    Change-Id: I228fef766b70ad4f3fc47b83cf113517eb9db99f

Change-Id: I70e9cc308b4f7c7681457a0b09dd73e5d1aebb73