Lockscreen settings per user

Move all lockscreen related settings to LockSettingsService.
LockPatternUtils uses this through IPC instead of Secure settings.
Migrate old settings to new database managed by LockSettingsService.
Passwords and patterns are stored in a new per-user location, except
 for the primary user, for backward compatibility.
KeyguardViewMediator and LockPatternKeyguardView listen for changes
to user and updates the lockscreen.

Settings provider will look for Lock settings in the LockSettings
service now for the entries that used to be stored in Settings.

Change-Id: I956cd5b95e2d9d45a6401af7e270e6a5aa2dcc98