In particular, link-local addresses are now tested as well.
Additionally, WebSocketTransport send/receive tests are extended
to check transport counters.
Change-Id: I5b35f498a5d8d70cb1f7a2bea3ce99d22370e050
Refs: #1428
This commit also renames the getAvailableInterfaceIp() API
to getTestIp(), and improves its expressiveness.
Change-Id: I4b0080fb5e85cd523305ecb14183ef6acb34b5cd
Refs: #3367