Follow-up on https://github.com/netobserv/netobserv-ebpf-agent/pull/509/

To avoid reaching MAX_INTERFACES, a limitation was introduced as a tradeoff, to not store the (interface,direction) couple when that same interface was already seen with a different direction, for  a given flow.

We can remove this limitation by introducing a new direction called BOTH (ie. ingress and egress).

This should be also handled in the console plugin, to display it accordingly.