UseHttpSys against IServiceCollection to support generic host

[chuanboz]

see aspnet/KestrelHttpServer#2498 for Kestrel.

similar issue exists for UseHttpSys, and it's even harder as MessagePump class is marked as internal.

'
public static IServiceCollection UseHttpSys(this IServiceCollection services)
{
services.AddSingleton<IServer, MessagePump>();
services.AddAuthenticationCore();
return services;
}
'

[muratg]

Design around this has changed. We don't need this anymore.

[chuanboz]

thanks @muratg , do you have a link to the changed design around this? just trying to understand the latest design better.

[Tratcher]

See aspnet/Hosting#1580