Add an assist mic to the navigation bar

I also updated the notification hook to use the new NotifcationCenter

Bug:110275838
Test: on dev device and in car
Change-Id: I28d42f6d37226028602fea4ac4d8901ba587a1ce
(cherry picked from commit 4691a983e2c4aaea68c4b642cca788c0933a5e12)