containerlab events

[FloSch62]

This PR add a containerlab events command.

The events command streams lifecycle updates for every Containerlab resource and augments them with interface change notifications collected from the container network namespaces. The output combines Docker's event feed with the netlink information that powers containerlab inspect interfaces, so you can observe container activity and interface state changes in real time without selecting a specific lab.

[hellt]

@FloSch62 thanks
Can you plz move the logic of this to clab package under events.go such that cmd package only contains the cli config bits and pieces

We try to make sure that cmd package is not used to do anything that is not CLI related