Add custom accessbility action to open glanceable hub

Added a section under KeyguardRootView which handles accessibility actions.
Added a custom action to open glanceable hub with Talkback on.

Bug: b/319140280
Test: atest AccessibilityActionsViewModelTest
Test: manual with Talkback on
Flag: ACONFIG com.android.systemui.communal_hub TEAMFOOD
Change-Id: Ie1b957e0cca749f24e96a79d4a8f13660601b030