Update titles & messages for password enrolment flows

Show different titles and description messages when
enrolling password under various conditions:
* personal lock verus work lock
* adding a new lock versus updating existing lock
* enrolling a PIN verus password versus pattern

Add icons to options in screen lock picker.

Add an option to redirect to work lock flow if the admin
has set device-wide password requirement.

Bug: 183922696
Test: m RunSettingsRoboTests -j ROBOTEST_FILTER=com.android.settings.password
Change-Id: I40417b113814659d3226a44eb7f9d553386e3c58