Add tethering offload HAL call via JNI

Additionally, try to locate java Control interface.

Test: as follows
    - built
    - flashed
    - booted
    - OffloadController log messages observed, but only ever
      "not enabled" messages (needs a supporting implementation)
Bug: 29337859
Bug: 32163131
Bug: 34361337
Merged-In: I5251d05f2d2fd732a33a8955a6c346b3a2401e46
Change-Id: I5251d05f2d2fd732a33a8955a6c346b3a2401e46
(cherry picked from commit 8784c80e42)

services/core/java/com/android/server/ConnectivityService.java

@@ -139,6 +139,7 @@ import com.android.server.connectivity.NetworkNotificationManager.NotificationTy
 import com.android.server.connectivity.PacManager;
 import com.android.server.connectivity.PermissionMonitor;
 import com.android.server.connectivity.Tethering;
+import com.android.server.connectivity.tethering.TetheringDependencies;
 import com.android.server.connectivity.Vpn;
 import com.android.server.net.BaseNetworkObserver;
 import com.android.server.net.LockdownVpnTracker;
@@ -789,8 +790,7 @@ public class ConnectivityService extends IConnectivityManager.Stub
         mTestMode = mSystemProperties.get("cm.test.mode").equals("true")
                 && mSystemProperties.get("ro.build.type").equals("eng");
 
-        mTethering = new Tethering(mContext, mNetd, statsService, mPolicyManager,
-                                   IoThread.get().getLooper(), new MockableSystemProperties());
+        mTethering = makeTethering();
 
         mPermissionMonitor = new PermissionMonitor(mContext, mNetd);
 
@@ -840,6 +840,14 @@ public class ConnectivityService extends IConnectivityManager.Stub
         mMultinetworkPolicyTracker.start();
     }
 
+    private Tethering makeTethering() {
+        // TODO: Move other elements into @Overridden getters.
+        final TetheringDependencies deps = new TetheringDependencies();
+        return new Tethering(mContext, mNetd, mStatsService, mPolicyManager,
+                IoThread.get().getLooper(), new MockableSystemProperties(),
+                deps);
+    }
+
     private NetworkRequest createInternetRequestForTransport(
             int transportType, NetworkRequest.Type type) {
         NetworkCapabilities netCap = new NetworkCapabilities();