Separate navigation bar

Move the logic related to navigation bar out of CarStatusBar into
StatusBar.

Note that some navigation bar logic related to notifications and
keyguard needs to stay in StatusBar for now. Will be refactored out in
separate CLs.

Bug: 142787842
Test: manual
Change-Id: Ie6bc5bccbc30aa53ea15e3f2ce19fd793bd6b38a