Higher Performance Packet Monitoring

[matt9j]

Right now haulage uses a naive userspace packet monitoring approach that involves additional packet copying. This has the benefit of placing few dependencies on the underlying system, but comes at the cost of performance. With LEO satellite use-cases looming for network-in-a-box community networks, it would be good to support an alternative traffic monitor more tightly integrated with something like dpdk/vpp, or the kernel conntrack system for performance up to the ~1gpbs range.