Moving FingerprintSettings to Kotlin

This change is the first of many, it will

1. Change java -> kotlin
2. Use the MVVM architecture
3. Be feature flagged

This change in particular is focused on transitions to and from various activities.

Enable feature via
adb shell setprop sys.fflag.override.settings_biometrics2_fingerprint true

Bug: 280862076
Test: atest FingerprintSettingsViewModelTest
Change-Id: I8eb5c30e6f2e92c256ae7c257a9d560439ba418f
Merged-In: I8eb5c30e6f2e92c256ae7c257a9d560439ba418f