Migrate demo 4 for module 4

[hansmbakker]

⚠️ Warning the old approach of having a shared ChatHistory object does not exist in Agent Framework
AgentSession is agent-specific and cannot be shared cross-agents.

Options are to

• use the workflow-approach
• use https://learn.microsoft.com/en-us/agent-framework/agents/conversations/storage?pivots=programming-language-csharp#simple-chathistoryprovider-implementation
• write a custom AIContextProvider?

@roycornelissen this needs some discussion

[hansmbakker]

@roycornelissen the WIP is in #40