Update Settings together with generateChallenge/revokeChallenge

The internal implementation of generate/revoke in system_server is now
asynchronous. To keep existing clients working, the manager classes
introduce a blocking version of the generateChallenge calls. This change
updates Settings to use the backward-compatible blocking calls.

Bug: 157790417

Test: Enroll fingerprint/face
Test: After enrollment, toggle setFeature or do subsequent enrollment
      in face/fingerprint settings
Change-Id: Ib4dfdc5f12530b938ab9b1745f5a19cd9e2eceee

tests/robotests/src/com/android/settings/testutils/shadow/ShadowFingerprintManager.java

@@ -31,4 +31,9 @@ public class ShadowFingerprintManager extends org.robolectric.shadows.ShadowFing
     protected List<Fingerprint> getEnrolledFingerprints(int userId) {
         return getEnrolledFingerprints();
     }
+
+    @Implementation
+    protected long generateChallengeBlocking() {
+        return 0L;
+    }
 }