support processing packet capture .pcap, pcapng files

[jtmoon79]

Support parsing packet capture .pcap and .pcapng

Support parsing packet capture files. There are Rust-based packet capture file parsers

• pcap_parser
• pcap-parser

Assuming pcap_parser works as well as I hope, a difficult part is deciding what to print from each packet. As a start, the most minimal information would be datetimestamp, frame source, frame destination. From there, the printing logic branches in many directions depending upon the packet content and the ability of pcap_parser to parse worthwhile data from it without panicking.