Add k8s annotations to the Envoy Proxy Service

*Description*:
Extend the [Envoy Proxy API](https://github.com/envoyproxy/gateway/blob/main/api/config/v1alpha1/envoyproxy_types.go) to allow a user to add more k8s annotations to the Envoy Proxy service. 

Relates to https://github.com/envoyproxy/gateway/issues/368#issuecomment-1243432619

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