Implement exported labels/annotations as outlined in the MCS spec

[tpantelis]

From spec:

"Most information about the service, including ports, backends, topology and session affinity, will continue to be stored in the Service objects, which are each name mapped to a ServiceExport. This does not apply for labels and annotations which are stored in ServiceExport directly in spec.exportedLabels and spec.exportedAnnotations. Exporting labels and annotations is optionally supported by MCS-API implementations. If supported, annotations or labels must not be exported from the metadata of the Service or ServiceExport resources."

Note that this feature is optional.