Introduce DisplayNavigationBarController

DisplayNavigationBarController is a class to control everything related
to external navigation bars. Belows are its tasks:
1. create external nav bars when:
   a. StatusBar.createNavigationBar()
   b. A system decoration supported display added
2. remove external nav bars when display is removed.
3. remove all external nav bars when StatusBar.destroy()

(Following Tasks)
1. Support SystemUiVisualibility for external nav bars
   (corresponding to b/117478341#3)
2. A design doc for refactor

Bug: 115978725
Bug: 117478341
Test: atest SystemUITests
Test: Manual - external nav bars still works

Change-Id: I17084c1be287ae7ccfb94b2d1302072a5d620e29