Refactor agent creation to use functional options and improve memory handling

- Updated examples in OrchestratorORM, SimpleAgent, and Syndicate to utilize functional options for agent creation instead of the builder pattern.
- Simplified memory management by introducing a new memory interface with functional options for adding and retrieving messages.
- Enhanced tests for memory and syndicate functionalities, including concurrency, error handling, and custom logic.
- Removed deprecated memory methods and added comprehensive tests for new memory implementation.

Author: Dieg0Code