Migrate AddAppNetworksFragment to use public getWifiConfiguration()

Field wifiConfiguration is @hide and cannot be
used, instead use public getter.

Bug: 138801922
Test: compiles
Exempt-From-Owner-Approval: Fix broken build
Change-Id: Idcaa2fee1950651b1a60e52838083ac8d75e9462

src/com/android/settings/wifi/addappnetworks/AddAppNetworksFragment.java

@@ -726,7 +726,7 @@ public class AddAppNetworksFragment extends InstrumentedFragment implements
             final Optional<AccessPoint> matchedAccessPoint = allAccessPoints
                     .stream()
                     .filter(accesspoint -> accesspoint.matches(
-                            uiConfigurationItem.mWifiNetworkSuggestion.wifiConfiguration))
+                            uiConfigurationItem.mWifiNetworkSuggestion.getWifiConfiguration()))
                     .findFirst();
             uiConfigurationItem.mLevel =
                     matchedAccessPoint.isPresent() ? matchedAccessPoint.get().getLevel() : 0;