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/core/api/src/main/java/org/onosproject/net/flow/DefaultTrafficSelector.java b/core/api/src/main/java/org/onosproject/net/flow/DefaultTrafficSelector.java
index 96b5066..e887112 100644
--- a/core/api/src/main/java/org/onosproject/net/flow/DefaultTrafficSelector.java
+++ b/core/api/src/main/java/org/onosproject/net/flow/DefaultTrafficSelector.java
@@ -293,7 +293,7 @@
         }
 
         @Override
-        public Builder matchIPv6ExthdrFlags(int exthdrFlags) {
+        public Builder matchIPv6ExthdrFlags(short exthdrFlags) {
             return add(Criteria.matchIPv6ExthdrFlags(exthdrFlags));
         }