Add focus handling to single press global action for TV

HSV: https://hsv.googleplex.com/6326833120280576

Bug: 402759931
Flag: com.android.systemui.tv_global_actions_focus
Test: atest GlobalActionsDialogLiteTest
Test: Manually test on device with and without the flag enabled.
Change-Id: I88e8d89cd7dc0746e7114473e8e87c1ccdfd5c6c