* Update M.A.AI.OpenAI implementations
- There was only a ChatClient-based agent. Add a Responses one, too.
- Fix the public extension methods to create OpenAI types even when not backed by the right OpenAI client.
- Add reusable AgentRunResponse{Update} to ChatResponse{Update} conversion routines that are then used by the OpenAI agents and elsewhere
* Address feedback
* Adding more test for workflow vizualization.
* Improving README for sample.
* More cleanup.
* Removing rendering of workflow visualization and adding basic support for mermaid format.
* Adding basic mermaid tests.
* Improving sample. Switching to another branch.
* About to merge from main.
* Formatting.
* More fromatting.
* Removng uneeded call to ToUpper.
* Adding README.
* Moving samples under workflow to workflows.
* Removing uneeded README for map-reduce sample.