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

src/com/android/settings/biometrics/face/FaceSettingsEnrollButtonPreferenceController.java

@@ -76,7 +76,7 @@ public class FaceSettingsEnrollButtonPreferenceController extends BasePreference
     @Override
     public void onClick(View v) {
         // If it's in multi window mode, do not start the introduction intent.
-        if (mListener != null && mListener.checkInMultiWindowMode()) {
+        if (mListener != null && mListener.onShowSplitScreenDialog()) {
             return;
         }
 
@@ -121,10 +121,10 @@ public class FaceSettingsEnrollButtonPreferenceController extends BasePreference
      */
     public interface Listener {
         /**
-         * Called to check whether it's in multi window mode
-         * @return Whether it's in multi window mode.
+         * Called to check whether to show dialog in split screen mode
+         * @return Whether split screen warning dialog shown.
          */
-        boolean checkInMultiWindowMode();
+        boolean onShowSplitScreenDialog();
 
         /**
          * Called when the user has indicated an intent to begin enrolling a new face.