Update confirm device credentials to spec, add fingerprint

- New strings in the screen.
- New layout/style.
- Clean up internal API's around it.
- Add fingerprint support if launched from externally
- Separate theme if launched from externally
- If launched from above Keyguard, use SHOW_WHEN_LOCKED flag

Change-Id: Icdf9bf9e0506841f24e8aab5f0f1d1f4b688951f