Formalize WifiConfiguration copy constructor

Copy constructor is used by WifiTrackerLib.

Bug: 138801922
Test: compiles
Change-Id: Icec13c808b875cde9d8204d55996bb18d8da1eb4

api/current.txt

@@ -30234,6 +30234,7 @@ package android.net.wifi {
 
   @Deprecated public class WifiConfiguration implements android.os.Parcelable {
     ctor @Deprecated public WifiConfiguration();
+    ctor @Deprecated public WifiConfiguration(@NonNull android.net.wifi.WifiConfiguration);
     method public int describeContents();
     method @Deprecated public android.net.ProxyInfo getHttpProxy();
     method @Deprecated @NonNull public String getKey();

wifi/java/android/net/wifi/WifiConfiguration.java

@@ -2590,9 +2590,8 @@ public class WifiConfiguration implements Parcelable {
         return mPasspointManagementObjectTree;
     }
 
-    /** copy constructor {@hide} */
-    @UnsupportedAppUsage
-    public WifiConfiguration(WifiConfiguration source) {
+    /** Copy constructor */
+    public WifiConfiguration(@NonNull WifiConfiguration source) {
         if (source != null) {
             networkId = source.networkId;
             status = source.status;