[http-server-csharp] no csproj or scaffolding is generated

[ArcturusZhang]

When I could generate the server code from a tsp, no scaffolding is generated at all.

This might be expected and by design, but I think to generate a scaffolding could play an important role on the API-first path.
If we are following the API-first path, we should have a way to keep the generated part of the server code clean and deterministic.