Allows related topics to show up for logged on users
- Introduces a new "Related Topics" block above suggested when related topics exist
- Renames `ai_embeddings_semantic_suggested_topics_anons_enabled` -> `ai_embeddings_semantic_suggested_topics_enabled` (given it is only deployed on 1 site not bothering with a migration)
- Adds an integration test to ensure data arrives correctly on the client
Sam