* change namespaces for agents and extension methods of the Microsoft.Agents.AI.OpenAI package
* remove unnecessary namespace
* remove unused namespaces
* fix compilation issues and rrolled back removed run methods
* sort usings
* add extension methods for AIAgent to work with OpenAI Responses primitives
* Move OpenAIChatClientAgent and OpenAIResponseClientAgent to samples
* sort usings
* sort usings
* Upgrade to .NET 10
- Require .NET 10 SDK
- Include net10.0 assets in all assemblies
- Move net9.0-only targets to net10.0
- Update LangVersion to latest
- Remove complicated distinctions between debug target TFMs and release target TFMs
- Remove unnecessary package dependencies when built into netcoreapp
- Clean up some ifdefs
- Clean up some analyzer warnings
* Fix CI