Move attach*Filter() and addArpEntry() methods to NetworkStack

The SocketUtils.attach*Filter and SocketUtils.addArpEntry methods
were added there because they could not be added as JNI inside
the NetworkStack. This was not possible because on Go devices,
the NetworkStack was a jar library. But now, Go also uses an APK.
Hence, move these methods to the NetworkStack.

Change-Id: I1d88a0f0be23f2b15d5103fa092b9bf982329d7c
Fix: 129433183
Test: atest NetworkStackTests FrameworksNetTests
diff --git a/Android.bp b/Android.bp
index 57a3db5..262e6f6 100644
--- a/Android.bp
+++ b/Android.bp
@@ -49,6 +49,27 @@
     manifest: "AndroidManifestBase.xml",
 }
 
+cc_library_shared {
+    name: "libnetworkstackutilsjni",
+    srcs: [
+        "jni/network_stack_utils_jni.cpp"
+    ],
+
+    shared_libs: [
+        "liblog",
+        "libcutils",
+        "libnativehelper",
+    ],
+    static_libs: [
+        "libpcap",
+    ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wno-unused-parameter",
+    ],
+}
+
 java_defaults {
     name: "NetworkStackAppCommon",
     defaults: ["NetworkStackCommon"],
@@ -56,6 +77,7 @@
     static_libs: [
         "NetworkStackBase",
     ],
+    jni_libs: ["libnetworkstackutilsjni"],
     // Resources already included in NetworkStackBase
     resource_dirs: [],
     jarjar_rules: "jarjar-rules-shared.txt",