Collect iptables -nvL -t mangle by support script

[nak3]

Description of changes:

aws-k8s-agent adds iptables for CONNMARK target to magle table.

e.g

# iptables -nvL -t mangle 
Chain PREROUTING (policy ACCEPT 25324 packets, 8496K bytes)
 pkts bytes target     prot opt in     out     source               destination         
    0     0 CONNMARK   all  --  ens5   *       0.0.0.0/0            0.0.0.0/0            /* AWS, primary ENI */ ADDRTYPE match dst-type LOCAL limit-in CONNMARK or 0x80
    0     0 CONNMARK   all  --  eni+   *       0.0.0.0/0            0.0.0.0/0            /* AWS, primary ENI */ CONNMARK restore mask 0x80

To collect mangle tables info, this patch adds iptables -nvL -t mangle
to aws-cni-support.sh.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[mogren]

Thanks, good addition.