onnxruntime

ce3b4eab - Implement Optional Metadata support and C# test support (#15314)

Implement Optional Metadata support and C# test support (#15314) ### Description Implement Optional Type metadata support in the library. Implement optional support in C# API along with metadata. Implement Sequence, Map, Optional test data support and test execution. Prune tests and provide more details for failing tests in C# code. Note, this PR does not enable running onnx test models in C++. ### Motivation and Context Opset18 optional type support.