frameworks: add persistent notification when USB OTG is connected

Tapping the notification will take the user into Storage settings, and
highlight the 'Unmount' option.

Change-Id: I650f3874a8295b2b8ffdaef78aff4b68e9cd574e
Signed-off-by: Roman Birg <roman@cyngn.com>
(cherry picked from commit 89a5500d1307eee3e356c425686002a93681d463)