Add IPv6 tethering coordinator

Add an IPv6TetheringCoordinator to TetheringMaster StateMachine, which
receives and processes NetworkState updates and passes the necessary IPv6
information to the revelant TetherInterfaceStateMachine.

Add an IPv6TetheringInterfaceServices to TetherInterfaceStateMachine, which
is responsible for adding local network routes and managing an IPv6
RouterAdvertisementDaemon.

Bug: 9580643
Change-Id: I3eaae460b80752e2115359d7bde873a1e9ea515a

core/java/android/net/LinkAddress.java

@@ -103,7 +103,7 @@ public class LinkAddress implements Parcelable {
     private boolean isIPv6ULA() {
         if (address != null && address instanceof Inet6Address) {
             byte[] bytes = address.getAddress();
-            return ((bytes[0] & (byte)0xfc) == (byte)0xfc);
+            return ((bytes[0] & (byte)0xfe) == (byte)0xfc);
         }
         return false;
     }