[Fingerprint] Fix link accessibility

Copied ExploreByTouchHelper, LinkAccessibilityHelper and LinkTextView
from setup wizard and switched fingerprint_settings_footer to use
LinkTextView, so that users can navigate to the link in TalkBack
mode.

Bug: 24343933
Change-Id: I0ff0c054510dfef4263ea223cb0044a4bddf321f
4 files changed