Add isConfirmationPromptSupported() method.

This will be used by the android.security.ConfirmationDialog.isSupported() and
is intended so that apps can know ahead of time whether the device implements
the ConfirmationUI HAL.

Bug: 63928580
Test: Manually tested.
Change-Id: I6347824b4e2330a93b7a7ffd7cf5b206009a564e
5 files changed