Introduce a reclaim policy for ephemerally created `Virtual IP` resources

[balpert89]

Summary

Similar to #1114 the same Reclaim Policy should be available for Virtual IP resources.

Basic example

apiVersion: compute.ironcore.dev/v1alpha1
kind: Machine
metadata:
  name: machine
spec:
  networkInterfaces:
  - ephemeral:
      networkInterfaceTemplate:
        metadata:
          creationTimestamp: null
        spec:
          ipFamilies:
          - IPv4
          ips:
          - ephemeral:
              prefixTemplate:
                metadata:
                  creationTimestamp: null
                spec:
                  ipFamily: IPv4
                  parentRef:
                    name: prefix
                  prefixLength: 32
          networkRef:
            name: network
          virtualIP:
             ephemeral:
               virtualIPTemplate:
                 metadata:
                   creationTimestamp: null
                 spec:
                   reclaimPolicy: Retain # this is the new field defining the "Retain" strategy for the corresponding `virtualIP` resource
                   ipFamily: IPv4
                   type: Public
    name: primary

Edit: updated the .spec.virtualIP structure to be in line with #1114

This instructs the controller to not remove the Virtual IP resource. When the managing Machine / NetworkInterface resource is deleted, the OwnerReference as well as the .spec.targetRef should be cleared.

Motivation

Resource saving for consuming teams, such as VPN configuration.

[Rohit-0505]

@balpert89, @afritzler, the example for enforcing ReclaimPolicy on ephemerally created VirtualIPs should indeed follow a similar approach to how ephemeral volumes handle reclaim policies in #1114
Here’s a revised example demonstrating how to structure this logic, please confirm if this looks good?

apiVersion: compute.ironcore.dev/v1alpha1
kind: Machine
metadata:
  name: machine
spec:
  networkInterfaces:
  - ephemeral:
      networkInterfaceTemplate:
        metadata:
          creationTimestamp: null
        spec:
          ipFamilies:
          - IPv4
          ips:
          - ephemeral:
              prefixTemplate:
                metadata:
                  creationTimestamp: null
                spec:
                  ipFamily: IPv4
                  parentRef:
                    name: prefix
                  prefixLength: 32
          networkRef:
            name: network
          virtualIP:
             ephemeral:
               virtualIPTemplate:
                 metadata:
                   creationTimestamp: null
                 spec:
                   reclaimPolicy: Retain # this is the new field defining the "Retain" strategy for the corresponding `virtualIP` resource
                   ipFamily: IPv4
                   type: Public
    name: primary