Add AspNetCoreSseServer sample (#81)

* Add AspNetCoreSseMcpTransport sample

* Fix build errors after rebase

* React to McpServerFactory changes

* Make Utf8JsonWriter non thread static

* Fix test errors caused by not rebasing the HttpLister changes on factory overhaul commit

samples/TestServerWithHosting/Program.cs

@@ -8,7 +8,7 @@ Log.Logger = new LoggerConfiguration()
                rollingInterval: RollingInterval.Day,
                outputTemplate: "{Timestamp:yyyy-MM-dd HH:mm:ss.fff zzz} [{Level:u3}] {Message:lj}{NewLine}{Exception}")
            .WriteTo.Debug()
-           .WriteTo.Console()
+           .WriteTo.Console(standardErrorFromLevel: Serilog.Events.LogEventLevel.Verbose)
            .CreateLogger();
 
 try
@@ -19,8 +19,7 @@ try
     builder.Services.AddSerilog();
     builder.Services.AddMcpServer()
         .WithStdioServerTransport()
-        .WithTools()
-        .WithCallToolHandler((r, ct) => Task.FromResult(new McpDotNet.Protocol.Types.CallToolResponse()));
+        .WithTools();
 
     var app = builder.Build();