Support cert-manager by way of supporting annotations and secretKeyRefs in zync managed routes

Managing custom certificates in OpenShift can be facilitated through automation via tools such as cert-manager. This is supported in OCP 4 as described here and in theory zync could support the use of this operator by allowing annotations & secretKeyRefs to be managed directly in zync itself (through admin portal/API).

This would solve all the requests around TLS settings and custom CA certificates we have already for zync.