Fix 5026428: Rework unlock attempt logic with active DPM to show better messages

Prior to this change, we didn't have a mechanism to warn the user when
they were approaching the wipe data threshold dictated by active DPMs.

Here's the new flow:

- If a device policy manager is installed and sets the max
password attempts, we start warning the user when they are within
a grace period of hitting the max (currently hard-wired to 5).

- We continue to show a dialog after each continued attempt
until the user reaches 0 remaining attempts.

- We now show a message when they hit 0 so they know why their device is
being reset.  The device will reboot and wipe data shortly after this final
dialog is shown.

Also increased the criteria for a pattern attempt from 3 dots to 4 dots
since the user can never set a pattern less than 4 in length. This will
greatly reduce the likelihood of a false wipe on the pattern unlock screens
without compromising security.

Change-Id: I28825ef21dfa2e2b6540e743252c6d50c41e5ad7