Use GLIF theme for screen lock confirmation

Theme the confirm password screen similar to setup wizard and screen
lock enrollment flow, so that we can start showing it during setup
wizard.
The new layouts are called "internal" because it's supposed to be
used only when another settings screen starts it. For external
intents from CONFIRM_DEVICE_CREDENTIAL, the existing theme and layout
are unchanged.

Bug: 32373672
Test: Run ConfirmLockPasswordTest with `am instrument`
Change-Id: Ib887a763a073e6e4b96264d08846827b2e5cbf52