1. Proposed title of this feature request
Enable additonal CoreDNS plugins

2. What is the nature and description of the request?
It should be possible to activate and configure additional CoreDNS plugins (e.g hosts plugin) in the dnses.operator.openshift.io/default manifest.

3. Why does the customer need this? (List the business requirements here)
Upgrade from OpenShift 3.11 to OpenShift 4 not possible.

4. List any affected packages or components.