Disruptor agent not working on MacOS on ARM chips

[pablochacin]

There are some issues regarding the compatibiity of the disruptor agent with test clusters deployed in MacOS running on ARM chips.

1. Iptables support on QEMU
   As reported by @dgzlopes iptables currently doesn't work under QEMU emulation on M1 laptops (iptables doesn't work on Intel based CentOS 7 Container. docker/for-mac#6297 (comment))

2. The agent fails to execute in the container

When injecting a fault, the script fails with this error message:

INFO[0000] target: ["hotrod-6cb64465cc-ts6qw"]           source=console
ERRO[0000] GoError: error invoking agent: Internal error occurred: error executing command in container: failed to exec in container: failed to start exec "052394429b3ee2563b9124e274b55117fb7b2af5556e6001ae7a4e82bc4c8388": OCI runtime exec failed: exec failed: unable to start container process: exec /usr/bin/xk6-disruptor-agent: exec format error: unknown 

        at reflect.methodValueCall (native)
        at file:///Users/dgzlopes/go/src/github.com/grafana/xk6-disruptor/examples/pod_disruptor.js:25:34(32)
        at native  executor=per-vu-iterations scenario=default source=stacktrace

[pablochacin]

Fixed by #84