Add arp_scan tome

[hulto]

Is your feature request related to a problem? Please describe.
We have an arp scan function but no tome to call it.

Describe the solution you'd like
Add a tome to call the arp_scan function and format the output.

Describe alternatives you've considered
Na

Additional context
Na

[nullmonk]

@hulto sys.get_ip() does not return the netmask but pivot.arp_scan() requires a netmask. Blocking until I can get netmask info

[hulto]

Ooh very fair.