refactor: migrate ExtraDim screen to xml/preferenceController style

- Updates the fragment test to be closer to integration test that could
  be used to verify the user interactions
- Use expressive style for the intensity slider

Bug: 406052931
Test: atest com.android.settings.accessibility
Test: manually verify the user interactions and UI on the screens
Flag: EXEMPT risk taken
Change-Id: Icbdd40bd1e7596058a74d0ca678508c60064a9d7