HttpClient and Stateless Worker Grain

This same demonstrates how to use HttpClient in a grain. It uses the same DI mechanism in your normal .NET Core app.

• The grain is marked at [StatelessWorker] because in this case, it keeps no state and Orleans is free to create multiple activations of this grain. You can read more about Stateless Worker grains here.
• We are using System.Json.Text serializer ReadFromJsonAsync method.