Evaluate options for nginx-ingress operator

In #179 (closed) we replaced the nginx-ingress operator with our forked nginx objects in order to support SSH. This works, but an operator is preferred in OpenShift environments.

This issue is a spike to answer these questions:

• What are the pros and cons of using our forked nginx objects vs an operator?
• What is the level of effort in getting our nginx changes merged into upstream? Is this desirable?
• Can we contribute to https://github.com/nginxinc/nginx-ingress-operator, or are we better off writing our own operator?