refactor: Enhance GenerationJobManager with In-Memory Implementations

- Introduced InMemoryJobStore, InMemoryEventTransport, and InMemoryContentState for improved job management and event handling.
- Updated GenerationJobManager to utilize these new implementations, allowing for better separation of concerns and easier maintenance.
- Enhanced job metadata handling to support user messages and response IDs for resumable functionality.
- Improved cleanup and state management processes to prevent memory leaks and ensure efficient resource usage.

packages/data-provider/src/types/agents.ts

@@ -195,6 +195,7 @@ export namespace Agents {
     userMessage?: UserMessageMeta;
     responseMessageId?: string;
     conversationId?: string;
+    sender?: string;
   }
   /**
    * Represents a run step delta i.e. any changed fields on a run step during