Improve IP4 ARP and IP6 ND Events Notification

Improve IP4 ARP and IP6 ND Events Notification

For L2 ARP termination, use both brodcast ARP request and reply
packets to provide MAC/IP binding events.

For IP4/IP6 neighbor adress resolution, send resolution events
if there is an address resolution attemp with a static neighbor
entry where both IP and MAC matches. This allow probe of an IP
neighbor with a static entry to confirm it is responding with
a reply matching that of the static entry.

Change-Id: Iffb923bb5aea3f9021436735d5ca06e7b24f966f
Signed-off-by: John Lo <loj@cisco.com>