Use distinct IDs to reuse agents in workflows

[homanp]

⚠️ Please check that this feature request hasn't been suggested before.

• I searched previous Ideas in Discussions didn't find any similar feature requests.
• I searched previous Issues didn't find any similar feature requests.

🔖 Feature description

A user should be able to reference a specific agent when creating a workflow like the example below:

workflows: 
  - superagent: <AGENT_ID>
     ....
  - openai_assistant: <ASSISTANT_ID>
    ...

📝 Additional Context

No response

Acknowledgements

• My issue title is concise and descriptive.
• I have searched the existing issues to make sure this feature has not been requested yet.
• I have provided enough information for the maintainers to understand and evaluate this request.