add auto build agent feature

[davidxwwang]

Why are these changes needed?

there is an AutoBuild feature on the 0.2 branch( https://microsoft.github.io/autogen/0.2/blog/2023/11/26/Agent-AutoBuild/), and I want to add this feature

Related issue number

#5573

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://github.com/microsoft/autogen/blob/main/CONTRIBUTING.md to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.