Fix terraform provider data sources

[bernardjkim]

Closes #46313, https://github.com/gravitational/customer-sensitive-requests/issues/412

See: https://developer.hashicorp.com/terraform/plugin/framework/data-sources for proper implementation of the Read method.

Note: We should consider updating the terraform-plugin-framework package. We're currently using v0.10.0 while the latest version is v1.14.x.

Changelog: Fix terraform provider data sources

Testing

terraform {
  required_providers {
    teleport = {
      source  = "terraform.releases.teleport.dev/gravitational/teleport"
      version = "18.0.0-dev"
    }
  }
}

provider "teleport" {...}

data "teleport_role" "test" {
  version = "v7"
  kind = "role"
  metadata = {
    name = "test"
  }
}

data "teleport_cluster_networking_config" "test" {
  version = "v2"
  kind = "cluster_networking_config"
}

output "role_name" {
  value = data.teleport_role.test.metadata["name"]
}

output "cluster_networking_config_id" {
  value = data.teleport_cluster_networking_config.test.id
}

# After terraform apply
$ terraform output
cluster_networking_config_id = "cluster-networking-config"
role_name = "test"

[public-teleport-github-review-bot]

@bernardjkim See the table below for backport results.

Branch	Result
branch/v16	Failed
branch/v17	Create PR