Allow tests to verify the result of PrimarySwitchPreference.setSwitchEnabled()

Bug: 265064188
Test: atest AppChannelsBypassingDndPreferenceControllerTest
Change-Id: Ic6f921fc0d0d6da03b05be8b2c2b0439241ebdd9

packages/SettingsLib/src/com/android/settingslib/PrimarySwitchPreference.java

@@ -23,6 +23,7 @@ import android.widget.Switch;
 
 import androidx.annotation.Keep;
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 import androidx.preference.PreferenceViewHolder;
 
 import com.android.settingslib.RestrictedLockUtils.EnforcedAdmin;
@@ -132,6 +133,11 @@ public class PrimarySwitchPreference extends RestrictedPreference {
         }
     }
 
+    @VisibleForTesting(otherwise = VisibleForTesting.NONE)
+    public boolean isSwitchEnabled() {
+        return mEnableSwitch;
+    }
+
     /**
      * If admin is not null, disables the switch.
      * Otherwise, keep it enabled.