C# output functions require object classes to use properties

Currently all our code assumes that the C# item class (T) defines the column names as properties on the object - e.g. https://github.com/Azure/azure-functions-sql-extension/blob/main/src/SqlAsyncCollector.cs#L272

This breaks if the object is defined with the properties as fields instead of properties, e.g.

```csharp
public class Product
{
public string Name;
public int Cost;
}
```

We should be able to support both ideally