Fix Accessibility button & gesture settings did not update correctly in Tablet device

Root Cause: ACCESSIBILITY_BUTTON_MODE only be updated in navigationbar, did not be updated in new-design taskbar.

Solution: Move updated function up to NavigationBarController, which
controlls NavigationBar and Taskbar.

Bug: 203173063
Test: manual test
Change-Id: Ib18fcd7062bf4e7627f4ffaeefd150c3d1055a47
2 files changed