ui/vnc: refactor arrays of addresses to SocketAddressList

ui/vnc: refactor arrays of addresses to SocketAddressList

Let's use SocketAddressList instead of dynamic arrays.
Benefits:
 - Automatic cleanup: don't need specific freeing function and drop
   some gotos.
 - Less indirection: no triple asterix anymore!
 - Prepare for the following commit, which will reuse new interface of
   vnc_display_listen().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@openvz.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220401143936.356460-2-vsementsov@openvz.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>