Add new device entry icon state "None"

The "none" state shows the device entry icon UI.
This is then used when the device may have
started running UDFPS; however, the device isn't
yet locked yet. This can be from a race condition
between the device starting UDFPS listening and
the isUnlocked state being updated.

This can also be consistently seen after a screen timeout which,
by default, won't lock the device for the first 5s.
During this time, show no device entry icon UI
(previously, the UDFPS icon would show which could
be misleading).

Fixes: 329880412
Flag: ACONFIG com.android.systemui.device_entry_udfps_refactor NEXTFOOD
Test: tap on UDFPS icon in AOD to trigger a successful face unlock.
observe unlock icon on the lockscreen
Test: Enroll UDFPS. Wait for display timeout, see no device entry icon
for first 5s when the device is still unlocked. After 5s, the device is
locked and the UDFPS icon shows.
Test: atest DeviceEntryIconViewModelTest

Change-Id: I59a391c201fad3dd56a015def4306ea120e55361