SystemUI: Add support for persistent usb drive notification.

Author: Adnan Begovic <adnan@cyngn.com>
Date:   Thu Jun 2 15:29:16 2016 -0700

    SystemUI: Add support for persistent usb drive notification.

      This option can be enabled via config_persistUsbDriveNotification

    Change-Id: I331a759aeb914e46e3ef4842896d3465d894707a
    TICKET: PAELLA-225

Author: Adrian DC <radian.dc@gmail.com>
Date:   Tue Jun 28 16:20:28 2016 +0200

    SystemUI: Restrict persistent USB drive notifications to USB disks

     * Without the addition of the isUsb check, a regular FAT32 MicroSD
        would have a persistent notification that is unwished

    Change-Id: I396a861702674d0a6a70beb5206fb4c7374ec85d

Author: Han Wang <416810799@qq.com>
Date:   Sat Sep 29 16:15:00 2018 +0200

    SystemUI: Remove overlay persistent usb drive overlay

    Change-Id: I40c5ba0d25b55cd51f38dbc10664dd964346ebd2

Change-Id: I331a759aeb914e46e3ef4842896d3465d894707a
(cherry picked from commit ca7ebb8b)