[Feature Request]: Redesign AgentBuilder's API and saved configs' JSON format

[LinxinS97]

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

• The current version of AgentBuilder requires users to provide a backbone model for build_manager and each agent. This can reduce user effort when creating agents but will limit the advanced usage.
• The current format of saved JSON files is self-defined, which is not general and may have corruptions with other methods.

Based on the above consideration, I think it is necessary to redesign the AgentBuilder's API and the JSON format for saved configs. I've marked the current API as "Experimental".

Describe the solution you'd like

No response

Additional context

No response

[qingyun-wu]

@LinxinS97, has this feature been added to the Captin agent? If so, could you close this issue? Thank you!