Change order for how FileDescriptors are returned in reflection service.

[bjorkstromm]

• FileDescriptors should be returned with the service first and then all dependencies after. All dependencies should occur after a FileDescriptor.

• See service reflection: include transitive closure for a file grpc/grpc-go#2949
  The Java implementation of the reflection service includes the entire transitive closure for a request file, in toplogical order such that a file's dependencies always appear after the file (so the requested file is first, with all of its dependencies after it).

• Fixes Issues with server reflection for code-first #141 once again 😄

// cc @mgravell @ChristianWeyer

Example using grpcurl with @ChristianWeyer's blazor app (https://github.com/thinktecture/blazor-webassembly-demo)

C:\temp>grpcurl localhost:5003 describe
ConfTool.Shared.Contracts.TimeService is a service:
service TimeService {
  rpc Subscribe ( .google.protobuf.Empty ) returns ( stream .ConfTool.Shared.Contracts.TimeResult );
}
ConfTool.Shared.Contracts.ConferencesService is a service:
service ConferencesService {
  rpc AddNewConference ( .ConfTool.Shared.Contracts.ConferenceDetails ) returns ( .ConfTool.Shared.Contracts.ConferenceDetails );
  rpc GetConferenceDetails ( .ConfTool.Shared.Contracts.ConferenceDetailsRequest ) returns ( .ConfTool.Shared.Contracts.ConferenceDetails );
  rpc ListConferences ( .google.protobuf.Empty ) returns ( .ConfTool.Shared.Contracts.IEnumerable_ConferenceOverview );
}
grpc.reflection.v1alpha.ServerReflection is a service:
service ServerReflection {
  rpc ServerReflectionInfo ( stream .grpc.reflection.v1alpha.ServerReflectionRequest ) returns ( stream .grpc.reflection.v1alpha.ServerReflectionResponse );
}

[bjorkstromm]

@ChristianWeyer, I've also fixed grpc-cli and it should be available on NuGet soonish.
https://www.nuget.org/packages/dotnet-grpc-cli/0.4.0
bjorkstromm/dotnet-grpc-cli@3d40df2

[bjorkstromm]

@mgravell I tried to check if protogen also needed a fix after this change... But I can't seem to get it to work.

dotnet run -f net5.0 -- --grpc list https://localhost:5003
Requesting gRPC service directory from 'https://localhost:5003'...
The type initializer for 'DefaultProxyCache`1' threw an exception.
   at ProtoBuf.Grpc.Configuration.ClientFactory.DefaultClientFactory.CreateClient[TService](CallInvoker channel) in /_/src/protobuf-net.Grpc/Configuration/ClientFactory.cs:line 91
   at ProtoBuf.GrpcTools.ExecuteAsync(String modeString, String uri, String serviceName, CodeGenerator codegen, String outPath, Dictionary`2 options) in c:\src\gh\protobuf-net\src\protogen\GrpcTools.cs:line 58
   at protogen.Program.Main(String[] args) in c:\src\gh\protobuf-net\src\protogen\Program.cs:line 141

[mgravell]

Merged. I'll see what I can find out about protogen, thanks

[ChristianWeyer]

Thank you!