Move BaseNetdUnsolicitedEventListener to frameworks/libs/net

Move BaseNetdUnsolicitedEventListener to frameworks/libs/net and
create a new library - netd-client for using.
Also remove netd_aidl_interface-unstable-java since netd-client
links to the stable one.

Bug: 174837473
Test: Manual test and check the log.
Change-Id: Id65142b8c13a6cccbfe387d4ab757967497546e6
diff --git a/Tethering/Android.bp b/Tethering/Android.bp
index d8557ad..272b4b9 100644
--- a/Tethering/Android.bp
+++ b/Tethering/Android.bp
@@ -26,7 +26,6 @@
     ],
     static_libs: [
         "androidx.annotation_annotation",
-        "netd_aidl_interface-unstable-java",
         "netlink-client",
         // TODO: use networkstack-client instead of just including the AIDL interface
         "networkstack-aidl-interfaces-unstable-java",
@@ -34,6 +33,7 @@
         "android.hardware.tetheroffload.control-V1.0-java",
         "net-utils-framework-common",
         "net-utils-device-common",
+        "netd-client",
     ],
     libs: [
         "framework-statsd.stubs.module_lib",