Refactor LockSettingsService to unify the handling of pattern and password

Also fix LockSettingsStorageTests. More unit tests on LockSettingsService
to be added in the next CL.

Bug: 33126408
Test: runtest frameworks-services -c com.android.server.LockSettingsStorageTests
Change-Id: I0f143b26fed1d5ae122fba3b57bd39c7793ad8d9
5 files changed