Add a flag to move the set screen lock dialog.

The move_set_screen_lock_dialog_to_settings_app flag will be used for
moving a dialog to prompt the user to set a screen lock to the Settings
app in order to apply theming.

Bug: 407327874, 406130727
Test: EXEMPT config only
Flag: android.multiuser.move_set_screen_lock_dialog_to_settings_app
Change-Id: I562269fb69fe34e018014f270be8c6f92cce8c39