WifiConfiguration: add local only networkId

When applications start LOHS, they need a way to connect to the
network on the same device.  The WifiConfiguration.networkId
will be set to the newly defined value to serve as a signal to
ConnectivityService that this request is for a local only
network connection.

Bug: 62076211
Test: frameworks/base/wifi/tests/runtests.sh
Change-Id: Iab5240a7b4f526f8bc72dd44cdba59e65faedcd1

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

@@ -67,6 +67,8 @@ public class WifiConfiguration implements Parcelable {
     public static final String updateIdentiferVarName = "update_identifier";
     /** {@hide} */
     public static final int INVALID_NETWORK_ID = -1;
+    /** {@hide} */
+    public static final int LOCAL_ONLY_NETWORK_ID = -2;
 
     /** {@hide} */
     private String mPasspointManagementObjectTree;