Create method to dynamically scale ingress router pods based on node roles

1. Proposed title of this feature request

• Create method to use a label selector to make the ingress router pod count match the number of nodes with a specific label. As an alternative, create a method to make the ingress router pod count match the number of Availability Zones (AWS).
• Additionally, potentially expose setting of the replica count for ingress router pods via the install-config

2. What is the nature and description of the request?

Add an option in IngressController CR to place router pods on specific nodes based on node labels/roles, and scale the count of the route pods deployed based on the count of matching nodes. Specifically, if the IngressController CR had a node selector option for the router pods, as well as an "autoscale" option. Then the deployment of the router-pods would have the number of replicas equal the number of nodes that match the selector, which would alsp be placed on the pods.

3. Why does the customer need this? (List the business requirements here)

Service Delivery needs this for OSD and ROSA clusters. See https://issues.redhat.com/browse/NE-361
4. List any affected packages or components.

IngressController, cluster-ingress-operator