Improve debugability of NetworkInterfaces

[lukasfrank]

Summary

Currently, it's difficult to find out the reason if a NetworkInterface is in Error state.

Basic example

Creating two NetworkInterfaces using the same IP obviously result in an Error state for the second NIC. It would helpful to have the reason attached to the object.

Possible approaches

1. Extending the state using status.conditions
   other kubernetes objects follow the same pattern. e.g. pods:

status:
  conditions:
  - lastProbeTime: null
    lastTransitionTime: "2024-07-12T13:20:16Z"
    status: "True"
    type: PodScheduled

2. Fire an Event
   Using Events and referencing the involved object can help to understand the state of an object by running k describe <obj>

e.g. pod events

Name:             dp-service-bf-tcrns
Namespace:        dp-service-bf-system
....
Events:
  Type     Reason            Age                 From               Message
  ----     ------            ----                ----               -------
  Normal   Created           20m                 kubelet            Created container init-dp-service
  Normal   Started           20m                 kubelet            Started container init-dp-service