Add icmp argument to allow shortcut for base protocol

[trkelly23]

The following tests for the mentioned use case:

1. Change protocol in the config file to non default tcp or udp.
2. Run trippy with shortcut --icmp
   Results:
   Config: protocol=icmp(v4, unprivileged) as-info=n/a details=off max-hosts=auto

This passed the basic use case please post comments if others should be run

Closes #649

[fujiapple852]

Thanks @trkelly23 - LGTM aside from small points above and the formatting (just run a default cargo fmt to fix that). Once fixed if you can squash to a single commit (ideally feat: add icmp command shortcut (#649 ) we should be good to merge this.

[trkelly23]

PR is squashed and the changes are ready to merge.

[fujiapple852]

Thanks, could you change the commit message as well? It’s a bit unclear as-is. My suggestion would be:

feat: add icmp command shortcut (#649)

[trkelly23]

Oops I missed the commit message which is all set and ready to merge.

[fujiapple852]

Merged, thanks @trkelly23 !