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
Change-Id: I5251d05f2d2fd732a33a8955a6c346b3a2401e46
diff --git a/services/core/jni/onload.cpp b/services/core/jni/onload.cpp
index 79c9b417..c3617e0 100644
--- a/services/core/jni/onload.cpp
+++ b/services/core/jni/onload.cpp
@@ -42,6 +42,7 @@
 int register_android_server_location_ContextHubService(JNIEnv* env);
 int register_android_server_location_GnssLocationProvider(JNIEnv* env);
 int register_android_server_connectivity_Vpn(JNIEnv* env);
+int register_android_server_connectivity_tethering_OffloadHardwareInterface(JNIEnv*);
 int register_android_server_hdmi_HdmiCecController(JNIEnv* env);
 int register_android_server_tv_TvUinputBridge(JNIEnv* env);
 int register_android_server_tv_TvInputHal(JNIEnv* env);
@@ -84,6 +85,7 @@
     register_android_server_location_ContextHubService(env);
     register_android_server_location_GnssLocationProvider(env);
     register_android_server_connectivity_Vpn(env);
+    register_android_server_connectivity_tethering_OffloadHardwareInterface(env);
     register_android_server_ConsumerIrService(env);
     register_android_server_BatteryStatsService(env);
     register_android_server_hdmi_HdmiCecController(env);