feat(agent): Make the AutoPlanChatManager customizable for planner

[FOkvj]

Description

When using AutoPlanChatManager, there are scenarios where I need to use my own planner, but currently the planner of AutoPlanChatManager is not customizable.

Checklist:

• My code follows the style guidelines of this project
• I have already rebased the commits and make the commit message conform to the project standard.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• Any dependent changes have been merged and published in downstream modules

[FOkvj]

@fangyinc