1/n: Refactor BiometricPrompt UI hierarchy

The UI is split into a few components now
 1) BiometricPromptContainerView - top level, contains the work profile
    background view, the panel (rounded background)
 2) BiometricPromptBiometricView - nested within, displays contents for
    biometric auth

The panel must be one level higher (in hierarchy) than the biometric
dialog to allow future non-biometric views to be added cleanly, and to
allow separate animations for the background/foreground.

Bug: 123378871
Test: Demo app with text that requires scrolling; dialog bounds are correct,
      view elements are contained within the dialog bounds
Test: atest BiometricDialogImplTest
Test: atest BiometricDialogViewTest
Test: atest AuthBiometricViewTest
Test: atest AuthBiometricFaceViewTest

Change-Id: Ie4e5a8641a10229154a1011afefacb823aadf565