Enable SDK

[velkymx]

add CSharp sdk and add sdk instance to csharp executor

[nolanpro]

C# SDK will not build. FilesApi.cs and RequestFilesApi.cs are attempting to send a List<System.IO.Stream> to ParameterToFile() which only accepts System.IO.Stream. I don't know if this is an annotation problem or a bug in openapi. SDK has been commented out in the default dockerfile for the csharp package.