Support for OpenShift Container Platform 4 deployment across different VPC (AWS Outpost)

1. Proposed title of this feature request
Support for OpenShift Container Platform 4 deployment across different VPC (AWS Outpost)

2. What is the nature and description of the request?
When installing OpenShift Container Platform 4 on AWS Outpost according to Installing a cluster on AWS with remote workers on AWS Outposts it's rather common that there is a different VPC configured for the resources running on AWS Outpost compared to the resources running in the respective region.

Yet, right now this is not supported as we can see that OpenShift Container Platform 4 tries to create a rule for traffic originating in the Security Group for the router-default classic ELB to a manually created Security Group that is used by the remote workers on AWS Outpost. This fails because the two Security Groups are in different VPCs. Also in this case there is no communication path between the default IngressController and the AWS Outpost worker nodes anyway as their router-default IngressController pods are running on nodes in the respective AWS region.

3. Why does the customer need this? (List the business requirements here)
In deployment scenarios like Installing a cluster on AWS with remote workers on AWS Outposts it will be fairly common that multiple different VPCs are being used and therefore authorization between different security groups available in different VPCs should not be created as this is not possible but mostly also not needed.

While generally the deployment works and no problem is found, the below error is constantly reported and therefore rather nasty, especially when troubleshooting.

W1121 14:32:57.343990       1 aws.go:3286] Error authorizing security group ingress "InvalidGroup.NotFound: You have specified two resources that belong to different networks.\n\tstatus code: 400, request id: b13d82ae-4635-4d17-8884-63c8e1740856"
W1121 14:32:57.344023       1 aws.go:4340] Error opening ingress rules for the load balancer to the instances: "error authorizing security group ingress: \"InvalidGroup.NotFound: You have specified two resources that belong to different networks.\\n\\tstatus code: 400, request id: b13d82ae-4635-4d17-8884-63c8e1740856\""
E1121 14:32:57.344086       1 controller.go:289] error processing service openshift-ingress/router-default (will retry): failed to ensure load balancer: error authorizing security group ingress: "InvalidGroup.NotFound: You have specified two resources that belong to different networks.\n\tstatus code: 400, request id: b13d82ae-4635-4d17-8884-63c8e1740856"
I1121 14:32:57.344125       1 event.go:294] "Event occurred" object="openshift-ingress/router-default" fieldPath="" kind="Service" apiVersion="v1" type="Warning" reason="SyncLoadBalancerFailed" message="Error syncing load balancer: failed to ensure load balancer: error authorizing security group ingress: \"InvalidGroup.NotFound: You have specified two resources that belong to different networks.\\n\\tstatus code: 400, request id: b13d82ae-4635-4d17-8884-63c8e1740856\""

4. List any affected packages or components.
OpenShift Container Platform 4 - Installation
OpenShift Container Platform 4 - kube-controller