🌱 Add TargetNamespace to cluster-template.yaml ControlPlaneEndpoint

[christopherhein]

User Story

As an operator I would like to get a cluster which works for vc-syncer across namespaces, so that I can sync workloads with vc-syncer.

Detailed Description

Right now with CAPN it doesn't add the namespace to the ControlPlaneEndpoint.Host which works fine in-cluster in the same namespace but isn't a valid FQDN in the certs for cross namespace traffic, al la the vc-syncer. To update this we need to add ${TARGET_NAMESPACE} from the clusterctl privder guide to the ControlPlaneEndpoint.Host for auto generation.

    host: "${CLUSTER_NAME}-apiserver.${TARGET_NAMESPACE}"

Anything else you would like to add:

Ref: #81

/kind feature
/milestone v0.1.x