additional metrics for key statistics

[drewrip]

Kube-netc currently reports 5 key metrics that were decided on from the beginning. To expand the use of the project we are thinking about what kind of metrics would be useful to implement next, specifically as per this post from WeaveScope.

There are a few considerations holding us back from simply writing these into the tracker, mainly whether or not our eBPF library can supply the necessary stats.