tests: add test to confirm supervisor iptables firewall rules are applied

[rcooke-warwick]

To ensure issues like this don't happen again:

balena-os/balena-supervisor#2252

As this was a problem that occured due to incompatibility between supervisor and OS this test belongs here

[rcooke-warwick]

Checks must be made for these in the BALENA_FIREWALL chain from the host OS

~# iptables -L -vn -t filter
...
Chain BALENA-FIREWALL (1 references)
 pkts bytes target     prot opt in     out     source               destination
 3444  506K ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0            state RELATED,ESTABLISHED
  228 14017 ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0            ADDRTYPE match src-type LOCAL
    0     0 ACCEPT     tcp  --  resin-vpn *       0.0.0.0/0            0.0.0.0/0            tcp dpt:48484
    0     0 ACCEPT     tcp  --  tun0   *       0.0.0.0/0            0.0.0.0/0            tcp dpt:48484
    0     0 ACCEPT     tcp  --  docker0 *       0.0.0.0/0            0.0.0.0/0            tcp dpt:48484
    0     0 ACCEPT     tcp  --  lo     *       0.0.0.0/0            0.0.0.0/0            tcp dpt:48484
    0     0 ACCEPT     tcp  --  supervisor0 *       0.0.0.0/0            0.0.0.0/0            tcp dpt:48484
    0     0 REJECT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:48484 reject-with icmp-port-unreachable
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:22222
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:2375
  439 38843 ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0            ADDRTYPE match dst-type MULTICAST
    7   588 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0
    0     0 ACCEPT     udp  --  balena0 *       0.0.0.0/0            0.0.0.0/0            udp dpt:53
   22  5010 RETURN     all  --  *      *       0.0.0.0/0            0.0.0.0/0
    0     0 REJECT     all  --  *      *       0.0.0.0/0            0.0.0.0/0            reject-with icmp-port-unreachable