Update Fingerprint21, add Fingerprint21UdfpsMock

1) It may not be practical in all cases to bump the HIDL to
   fingerprint2.3. So, give the framework a way to override this
   parameter.
2) Updates Fingerprint21 so the HAL callback is a static inner class.
   This A) allows subclasses to extend/override its functionality, and
   B) is necessary now because the callback needs to be created prior
   to Fingerprint21 construction (see 3 below)
3) Changes Fingerprint21 so that several objects are created before
   its constructor. This is necessary because Fingerprint21's
   constructor requires usage of the HAL, which implies the callback
   must be ready, since using the HAL requires a valid callback. In
   other words, the callback must be created before
   Fingerprint21UdfpsMock invokes Fingerprint21's constructor.
4) UDFPS accept must be touched within 10s of sensor auth succeeding
5) Shows debug messages on UdfpsOverlay since fingerprint sensor no
   longer gives feedback, etc

Bug: 163864182
Test: adb shell settings put secure ... (see defs in
      Fingerprint21UdfpsMock)
      adb shell stop && adb shell start
Change-Id: I07c3801024087f2e8ef10f125d20cb536aefbd91