Add custom message to bouncer

Add a message to bouncer when we are showing to show the reason we are
authing bouncer. This is set in dismiss with action as we intend to
authenticate to perform some action.

Fixes: 277278610
Test: longpress lockscreen and open lockscreen settings. Open bouncer
with udfps enabled and not enabled.

Change-Id: I82a5aea6779a60e200921f0743882cd03305185c