Move NetworkUtils used by NetworkStack

Depending on usage move into NetworkStackUtils or shared
Inet4AddressUtils.

Test: atest FrameworksNetTests NetworkStackTests
Bug: 112869080
(Cherry-pick of aosp/881952)
Change-Id: Ie20dcee375b377236004a7689890729493aca857
diff --git a/Android.bp b/Android.bp
index 56f3c23..813e98c 100644
--- a/Android.bp
+++ b/Android.bp
@@ -912,6 +912,27 @@
     api_dir: "aidl/networkstack",
 }
 
+filegroup {
+    name: "framework-networkstack-shared-srcs",
+    srcs: [
+        // TODO: remove these annotations as soon as we can use andoid.support.annotations.*
+        "core/java/android/annotation/NonNull.java",
+        "core/java/android/annotation/Nullable.java",
+        "core/java/android/annotation/IntDef.java",
+        "core/java/android/annotation/UnsupportedAppUsage.java",
+        "core/java/android/util/LocalLog.java",
+        "core/java/com/android/internal/annotations/VisibleForTesting.java",
+        "core/java/com/android/internal/util/HexDump.java",
+        "core/java/com/android/internal/util/IState.java",
+        "core/java/com/android/internal/util/MessageUtils.java",
+        "core/java/com/android/internal/util/Preconditions.java",
+        "core/java/com/android/internal/util/State.java",
+        "core/java/com/android/internal/util/StateMachine.java",
+        "core/java/com/android/internal/util/WakeupMessage.java",
+        "core/java/android/net/shared/*.java",
+    ]
+}
+
 // Build ext.jar
 // ============================================================
 java_library {