[Feat]: [Feat]: Add metadata parameter to TaskUpdater.update_status method

[yokonao]

Is your feature request related to a problem? Please describe.

Currently, the TaskUpdater.update_status() method does not allow passing metadata, even though the underlying TaskStatusUpdateEvent type already has a metadata field.

When implementing agents, there are situations where we need to attach additional context or custom data to status updates
(e.g., progress percentages, error codes, or domain-specific information). Without this capability, we have to work around the limitation by using the lower level API EventQueue.enqueue_event.

Describe the solution you'd like

Add an optional metadata parameter to the TaskUpdater.update_status() method:

async def update_status(
    self,
    state: TaskState,
    message: Message | None = None,
    final: bool = False,
    timestamp: str | None = None,
    metadata: dict[str, Any] | None = None,  # New parameter
) -> None:

The implementation would pass this metadata to the TaskStatusUpdateEvent:

await self.event_queue.enqueue_event(
    TaskStatusUpdateEvent(
        task_id=self.task_id,
        context_id=self.context_id,
        final=final,
        metadata=metadata,  # Pass metadata here
        status=TaskStatus(
            state=state,
            message=message,
            timestamp=current_timestamp,
        ),
    )
  )

This change would:

• Maintain backward compatibility (optional parameter)
• Provide consistency with other TaskUpdater methods
• Enable developers to attach metadata to status updates

Describe alternatives you've considered

N/A

Additional context

N/A

Code of Conduct

• I agree to follow this project's Code of Conduct