Move Inet[4]AddressUtils to libs/net

The classes should not be picked up from frameworks/base, as they are
part of several mainline modules.

Also refine comments in DhcpResults following feedback in previous
change.

(cherry-pick from internal branch skipping wifi classes; no other
conflict)

Bug: 151052811
Test: m; manual: flashed, wifi and telephony working
Test: atest NetworkStackCoverageTests
Merged-In: I7074651c6a2a7a6b11bcf13cc4bb03833d7d655f

Change-Id: I7074651c6a2a7a6b11bcf13cc4bb03833d7d655f

core/java/android/net/NetworkUtils.java

@@ -21,13 +21,14 @@ import static android.system.OsConstants.AF_INET6;
 
 import android.annotation.NonNull;
 import android.compat.annotation.UnsupportedAppUsage;
-import android.net.shared.Inet4AddressUtils;
 import android.os.Build;
 import android.system.ErrnoException;
 import android.system.Os;
 import android.util.Log;
 import android.util.Pair;
 
+import com.android.net.module.util.Inet4AddressUtils;
+
 import java.io.FileDescriptor;
 import java.math.BigInteger;
 import java.net.Inet4Address;

core/java/android/net/StaticIpConfiguration.java

@@ -21,11 +21,11 @@ import android.annotation.Nullable;
 import android.annotation.SystemApi;
 import android.annotation.TestApi;
 import android.compat.annotation.UnsupportedAppUsage;
-import android.net.shared.InetAddressUtils;
 import android.os.Parcel;
 import android.os.Parcelable;
 
 import com.android.internal.util.Preconditions;
+import com.android.net.module.util.InetAddressUtils;
 
 import java.net.InetAddress;
 import java.util.ArrayList;

tests/net/common/java/android/net/DhcpInfoTest.java

@@ -16,8 +16,7 @@
 
 package android.net;
 
-import static android.net.shared.Inet4AddressUtils.inet4AddressToIntHTL;
-
+import static com.android.net.module.util.Inet4AddressUtils.inet4AddressToIntHTL;
 import static com.android.testutils.MiscAssertsKt.assertFieldCountEquals;
 import static com.android.testutils.ParcelUtilsKt.parcelingRoundTrip;