expose config: Allow setting a loadBalancerClass in the loadbalancer config

Environmental Info: Host Cluster Version: not relevant

Node(s) CPU architecture, OS, and Version: not relevant

Host Cluster Configuration: I have a host cluster that has 2 loadbalancer implementation for different purposes.

K3K Cluster Configuration: not relevant

Describe the bug: If I want to spin up a k3k cluster and expose it via loadbalancer, k3k always picks the default implementation. I would like to be able to configure the desired loadBalancerClass in the cluster CRD.

See https://kubernetes.io/docs/concepts/services-networking/service/#load-balancer-class

Steps To Reproduce: In a cluster with two or more available loadBalancer implementations, create a shared cluster with the following spec:

apiVersion: k3k.io/v1beta1
kind: Cluster
  name: test-cluster
  namespace: testing
spec:
  expose:
    loadBalancer: {}
  mode: shared

Expected behavior: I can set the desired loadBalancerClass in the CRD.

Actual behavior: The controller tries to create a loadbalancer on the default loadbalancer implementation for the cluster.