Ensure that input is disabled when locked out.

In the password security method, if we are locked out, one can use the
ime enter button to invoke #verifyPasswordAndUnlock which sets
setPasswordEntryInputEnabled(true). This allows the user to input a
password and bypass  the security screen when locked out.

The solution is to ensure that setPasswordEntryInputEnabled(false) when
locked out to prevent any input at all in the text field. Additionally,
we cache the locked out state and use this as a condition to proceed or
not when verifying the password to unlock.

Fixes: 284441628
Test: tested lockout with password, pin, and pattern, with power cycling
and doing various inputs.
Test: added a unit test

Change-Id: Iceb71eb2a79e14e3c62f7ac63c3c06275af0cecf