Add FingerprintDialog API and related plumbing

This commit adds the plumbing which sends the signals from the API
to the component in SysUI. The dialog will be implemented in another
CL in this topic.

Bug: 67497360

Test: Modify Settings to use the new API
Test: FingerprintDialogImpl is able to notify FingerprintDialog clients
      of user events
Test: System dialog is dismissed when client application is killed
      unexpectedly
Test: Open FP settings, lock device, authenticate, authenticate. Repeat

Change-Id: Id28ec9691646bed765dc069cceb4678d9f6db92e