Add TLS termination to DC-API ingress via cert-manager

Summary

The DC-API ingress resource (kubernetes_ingress_v1.dc_api) in modules/management/dc-controlplane-services/main.tf currently exposes dcapi_hostname over plain HTTP with no TLS termination. TLS termination was intentionally deferred as this endpoint is internal-only (management network), but should be added before any broader exposure.

Work Required

• Wire cert-manager into the dcapi-controlplane-rke2 cluster (Issuer/ClusterIssuer)
• Add a tls block to kubernetes_ingress_v1.dc_api referencing a cert-manager-issued or pre-created TLS secret for var.dcapi_hostname
• Update outputs.tf to expose the DC-API URL as https:// once TLS is in place
• Ensure the TLS secret name aligns with the cert-manager Certificate resource or pre-provisioned secret

References

• PR: https://github.com/wso2/open-cloud-datacenter/pull/91
• Review comment: https://github.com/wso2/open-cloud-datacenter/pull/91#discussion_r3189812963

/cc @HiranAdikari