Apply new labels model to container cluster and edgenetwork resources

[modular-magician]

Part of hashicorp/terraform-provider-google#16219

Apply new labels model to google_container_cluster, google_edgenetwork_network and google_edgenetwork_subnet

Release Note Template for Downstream PRs (will be copied)

container: three label-related fields are now in `google_container_cluster` resource. `resource_labels` field is non-authoritative and only manages the labels defined by the users on the resource through Terraform. The new output-only `terraform_labels` field merges the labels defined by the users on the resource through Terraform and the default labels configured on the provider. The new output-only `effective_labels` field lists all of labels present on the resource in GCP, including the labels configured through Terraform, the system, and other clients.

container: made three fields `resource_labels`, `terraform_labels`, and `effective_labels` be present in `google_container_cluster` datasources. All three fields will have all of labels present on the resource in GCP including the labels configured through Terraform, the system, and other clients, equivalent to `effective_labels` on the resource.

edgenetwork: three label-related fields are now in `google_edgenetwork_network ` and `google_edgenetwork_subnet` resources. `labels` field is non-authoritative and only manages the labels defined by the users on the resource through Terraform. The new output-only `terraform_labels` field merges the labels defined by the users on the resource through Terraform and the default labels configured on the provider. The new output-only `effective_labels` field lists all of labels present on the resource in GCP, including the labels configured through Terraform, the system, and other clients.

Derived from GoogleCloudPlatform/magic-modules#11320

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