Manually merge CL 2175149 to master for green build

Refactor accessibility button support detection

- Moves logic to detect devices capable of supporting the
  accessibility button into AccessibilityManager from
  SettingsLib to avoid issues with resource shifting in the
  SUW binary

Bug: 37650567
Test: Existing SUW Robolectric
Change-Id: Ibb2aaa3c2f79570df768cfa796fa890988ef82cc