Update face/fingerprint consent screen UIs

Makes the following UI changes to the consent screens for face and
fingerprint enrollment:
- Sets description text in XML rather than in Java
- Highlight both primary and secondary buttons
- Use extracted highlight color for all icons

Test: Manually tested SUW flow

Bug: 188922185
Bug: 187458628
Bug: 183710943
Change-Id: I39d9b990dcbb82f443515a2175766dc51ca1180c