Check password blacklist when setting credential

If the password is valid by all other checks, see if it is present on
the blacklist and disallow it if it is.

Test: set a password blacklist, try and set a blacklisted password and
see an explanation, set a non-blacklisted password successfully.
Test: make ROBOTEST_FILTER=ChooseLockPasswordTest RunSettingsRoboTests

Bug: 63578054
Fix: 65659151
Change-Id: Id155b824ad4b5839c23b6f5fd3fdfdcfc78c3df1