Add Kubernetes kafka Recipe - Terraform

Overview of the Resource type and Recipe

Radius.Messaging/kafka only has an Azure recipe today. Create a Kubernetes Recipe in Terraform for provisioning Kafka in-cluster.

Acceptance criteria

1. A Kubernetes Terraform recipe at Messaging/kafka/recipes/kubernetes/terraform/ (main.tf + var.tf) that provisions Kafka in-cluster and maps topic.
2. Emits the Radius result object with the resource type's outputs.
3. Recipe entry added to the default Kubernetes recipe pack (recipepack/kubernetes/default-recipepack.bicep).
4. README for Resource type and Recipe; manual testing with make test-recipe.

Additional context

Example: Data/postgreSqlDatabases/recipes/kubernetes/terraform/; contribution guide docs/contributing/contributing-resource-types-recipes.md.