Count isActivityEmbedded() state to show split screen warning dialog

According to Activity#isInMultiWindowMode() API design,
When the Task is in fullscreen windowing mode, and the app is in
ActivityEmbedding split (two activities split left and right),
Activity.isInMultiWindowMode() == true.

With the reason, we should consider additional condidion for
foldable device in unfolded mode, while settings activities
config to embedded activity, we can't only count on
isInMultiWindowMode() for split-screen mode

Bug: 278176550
Bug: 276938441
Test: atest CombinedBiometricProfileSettingsTest
Test: atest FingerprintSettingsFragmentTest
Test: manaul go to split screen mode and try to enroll face
Test: manual unfold device and enroll finger or face
Change-Id: I02bd223f27889e74e67b73051531a5b4554f3de1