Added buttons for entering and exiting customize mode

+ added buttons for adding shortcut.

Fix: 373632868
Fix: 373619545
Test: Manual - ensure UI corresponds with UI mocks.
Flag: com.android.systemui.keyboard_shortcut_helper_shortcut_customizer
Change-Id: Ia8a695049cbc2dfc2a638f31d06b2708aef20313
6 files changed