Fix developer option not being enabled.

- when screen lock is set, we will start the activity to check user's
credential. Override onActivityResult() and call BuildNumberPreferenceController's
method accordingly, so that we will checks the password confirm result and enable
the developer options if it is success.

Change-Id: Ie2df644c53430ad4eb394480348d956177804ec3
Fixes: 73102865
Test: make RunSettingsRoboTests