Adding embeddings/RAG support to the Koog-based AI agent in Confetti

Recently I started looking at reworking the recommendation feature in the Confetti Compose Multiplatform sample (which uses Apollo Kotlin to consume a GraphQL API serving data for various conferences). The new implementation uses a Koog AIAgent with a ToolRegistry that includes session and speaker tools, giving the LLM on-demand access to the conference data it needs.