UX Polishing with new Biometric APIs

This change polishes our UI/UX to contain the PromptView that allows for
embedding the more option within it.

As a part of the polish, we met with our BiometricTeam POC and
confirmed the recent changes. We validated the button alignment is as
expected, we made headway on the strings bug, and we confirmed expected
fallback behaviour when no negative button exists.

During CL iteration, some changes raised UX discussion. Namely, a string
that comes from the provider is nullable, and using the existing
approach could at most be a fallback. Secondly, we had discussions
around DEVICE_CREDENTIAL being imbued directly, which matched the mocks,
but raised questions on whether we need a CANCEL instead, and on what to
do in the case of only DEVICE_CREDENTIAL (where it presently goes into
the PIN/Pattern/Etc... screen). This solves the single case, and we have
a path to allow 'CANCEL' instead of the present mocks for device cred
after discussion that will be in a follow up implementation.

Thus, this change ensures the new API is used, confirms the flows are as
expected in test, and kick started discussions that can be followed up.

Bug: b/333445112
Test: Heavily tested, video will be attached to bug pre submission

Change-Id: Ic7713490c0a85a9b6a3286bc0ec61743ac9ef222