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
daaf8f8bc9