1. Proposed title of this feature request:
[GCP] IngressController should support the definition of loadBalancerIP on the LoadBalancer service

2. What is the nature and description of the request?
When an ingress controller is deployed with LoadBalancerService as endpointPublishingStrategy should be possible to define the loadBalancerIP of the service exposing the router.

Here an example of CRD:

apiVersion: operator.openshift.io/v1  
kind: IngressController  
metadata:  
  namespace: openshift-ingress-operator 
  name: default  
spec:  
  endpointPublishingStrategy:  
    type: LoadBalancerService  
    loadBalancer:  
      scope: Internal  
      loadBalancerIP: xxx.yyy.zzz.www  

3. Why does the customer need this?
In this way the cluster admin has control over the public IP used by the ingress router, simplifying the automation of the external LB configuration.
Without this feature the admin needs to patch the service complicating the management of the cluster.
If the ingress is for some reasons re-deployed the admin needs to patch again the service.

4. List any affected packages or components.
Ingress Controller