.Net: Add GenAI support to Connectors.Onnx

[feiyun0112]

@stephentoub invite me to Contribute https://github.com/feiyun0112/SemanticKernel.Connectors.OnnxRuntimeGenAI to Microsoft.SemanticKernel.Connectors.Onnx

https://github.com/feiyun0112/SemanticKernel.Connectors.OnnxRuntimeGenAI/issues/4

[stephentoub]

Excellent, thanks! I'll take a look soon.

[rogerbarreto]

@feiyun0112 Thanks for the contribution!

[stephentoub]

@RogerBarreto, I suggest we not hold this waiting for the ONNX runtime library targeting netstandard2.0. You ok with that?

[markwallace-microsoft]

@feiyun0112 Two things for this PR

1. Can you add unit tests to cover the new functionality, our target is 80% code coveregae
2. Can you run dotnet format and commit the resulting changes

[stephentoub]

@RogerBarreto, what are the next steps for this one?

[arafattehsin]

@stephentoub @RogerBarreto This is definitely going to be an awesome addition. Thanks for considering it. Big thanks to you @feiyun0112 for this as well :)