Support multiple hosts

Hi,

First off, SuperSocket v2 is looking great! Especially all the support for .NET Core and the Hosted Services.

It would be nice to be able to be able to have multiple servers running in one process. Rather than your SuperSocketHostBuilder it could be refactored so you could do something like:

        static async Task Main(string[] args)
        {
            await CreateHostBuilder(args).Build().RunAsync();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureLogging((hostCtx, loggingBuilder) =>
                {
                    loggingBuilder.AddConsole();
                })
                .UseSuperSocket<TextPackageInfo>(hostBuilderContext =>
                {
                    //Configure server 1
                    return new ServerOptions();
                })
                .UseSuperSocket<TextPackageInfo>(hostBuilderContext =>
                {
                    //Configure server 2
                    return new ServerOptions();
                });

I would be happy to look at this and submit a PR if you are interested?

I think it should be possible to keep all the existing functionality as is without any breaking changes.

[kerryjiang]

I did an enhancement about it. Check out the new added test case in the main test.

[markgould]

I think they could be registered under the scope of the individual server. I’ll see if I can put together a proof of concept to see what you think.

I agree that for bigger services splitting them and using containers is probably best but for small projects sometimes that is overkill.