Fix deadlock in KeyguardDisableHandler

At the moment KeyguardDisableHandler calls into DevicePolicyManager
to retrive the aggregated password quality for the current user
while holding the WindowManager lock. This is a lock inversion
and causes deadlock. To fix this, introduce a per-user password quality
cache in DevicePolicyCache and switch KeyguardDisableHandler
to use that instead.

Test: manual
Fix: 129087668
Change-Id: I8c02ca442dde76ed350f22ac04a52adc82d21d00