Move shared methods to net shared lib

The NetworkUtils.getNetworkPart() method is used by Settings
and wifi. NetworkUtils is inside the incoming connectivity
module. It will become inaccessible outside the module, so
move the shared methods to shared lib and also move the
related helper method.

The corresponding usgae is also updated.

Bug: 172183305
Test: atest FrameworksNetTests
Change-Id: I47410afa27aad61f63759df41be959f323c1d100
diff --git a/framework/src/android/net/IpPrefix.java b/framework/src/android/net/IpPrefix.java
index e7c8014..e970065 100644
--- a/framework/src/android/net/IpPrefix.java
+++ b/framework/src/android/net/IpPrefix.java
@@ -23,6 +23,8 @@
 import android.os.Parcelable;
 import android.util.Pair;
 
+import com.android.net.module.util.NetUtils;
+
 import java.net.Inet4Address;
 import java.net.Inet6Address;
 import java.net.InetAddress;
@@ -58,7 +60,7 @@
             throw new IllegalArgumentException(
                     "IpPrefix has " + address.length + " bytes which is neither 4 nor 16");
         }
-        NetworkUtils.maskRawAddress(address, prefixLength);
+        NetUtils.maskRawAddress(address, prefixLength);
     }
 
     /**
@@ -189,7 +191,7 @@
         if (addrBytes == null || addrBytes.length != this.address.length) {
             return false;
         }
-        NetworkUtils.maskRawAddress(addrBytes, prefixLength);
+        NetUtils.maskRawAddress(addrBytes, prefixLength);
         return Arrays.equals(this.address, addrBytes);
     }
 
@@ -203,7 +205,7 @@
     public boolean containsPrefix(@NonNull IpPrefix otherPrefix) {
         if (otherPrefix.getPrefixLength() < prefixLength) return false;
         final byte[] otherAddress = otherPrefix.getRawAddress();
-        NetworkUtils.maskRawAddress(otherAddress, prefixLength);
+        NetUtils.maskRawAddress(otherAddress, prefixLength);
         return Arrays.equals(otherAddress, address);
     }