Fixing App Selector scrolling with Talkback

RecyclerView stopped scrolling because we're setting custom AccessibilityDelegate for it but that overrides the delegate that RecyclerView sets for itself internally. Solution is to add new RecyclerViewExpandingAccessibilityDelegate that extends RecyclerViewAccessibilityDelegate and uses AppListAccessibilityDelegate internally so that we still keep auto-expanding behaviour.

Fixes: 271530637
Test: manual, videos attached
Change-Id: Ie3fdff049ad9c82ad4255cdbaddede54378fff4d