ONOS-1756: Improve CLI auto completers

- Add more ICMP types and codes
- Add completer for --icmp6Type
- Add completer for --icmp6Code
- Add completer for --extHdr
    It is a multiValued option.
    For example, the following command will match an IPv6 packet with both fragment and routing extension header:
    add-point-intent --ethType IPV6 --extHdr FRAG --extHdr ROUTING
    NOTE: OVS 2.3.1 does not support OFPXMC_OFB_IPV6_EXTHDR match field yet.
- Change parameter of TrafficSelector.matchIPv6ExthdrFlags() from int to short since that field is 9 bits only

Change-Id: I55944399f3985f2cc09330a726f21983de273341
diff --git a/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowEntryBuilder.java b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowEntryBuilder.java
index c1253a2..5ee0418 100644
--- a/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowEntryBuilder.java
+++ b/providers/openflow/flow/src/main/java/org/onosproject/provider/of/flow/impl/FlowEntryBuilder.java
@@ -622,7 +622,7 @@
                 builder.matchIPv6NDTargetLinkLayerAddress(mac);
                 break;
             case IPV6_EXTHDR:
-                builder.matchIPv6ExthdrFlags((int) match.get(MatchField.IPV6_EXTHDR)
+                builder.matchIPv6ExthdrFlags((short) match.get(MatchField.IPV6_EXTHDR)
                                             .getValue());
                 break;
             case OCH_SIGID: