fix: adjust behavior of isUVPAA for Clank

Instead of returning true if fingerprint and/or screenlock is
available, isUVPAA only returns true if and only if fingerprint
is available. This is done by replacing
keyguardManager.isDeviceSecure() to
fingerprintManager.hasEnrolledFingerprints().

Note that this is an intentional narrowing in scope from the behavior
defined in the WebAuthn spec.

Bug: 936539
Change-Id: Ie94bb2bfe0387ea7055a59a7a08d0a8d560f843e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1505850
Reviewed-by: David Trainor <dtrainor@chromium.org>
Reviewed-by: Kim Paulhamus <kpaulhamus@chromium.org>
Commit-Queue: Suzy Li <suzyli@google.com>
Cr-Commit-Position: refs/heads/master@{#640083}
3 files changed