Support Create/DeleteTopics v0-2 with admin gate

[novatechflow]

Summary

• Extend CreateTopics/DeleteTopics support to v0-2, including request parsing and response encoding.
• Add admin API gate via KAFSCALE_ALLOW_ADMIN_APIS (returns TOPIC_AUTHORIZATION_FAILED when disabled).
• updated operations.md to document the new switch
• Add e2e Kafka CLI admin test using kafka-topics.sh create/delete and update protocol docs.

Testing

• make test (PASS)
• make test-produce-consume (PASS)