Add basic zipkin extension

This starts the zipkin container, but `--dtrace zipkin=...` is still
needed for now.

src/Microsoft.Tye.Extensions/WellKnownExtensions.cs

@@ -5,6 +5,7 @@
 using System;
 using System.Collections.Generic;
 using Microsoft.Tye.Extensions.Dapr;
+using Microsoft.Tye.Extensions.Zipkin;
 
 namespace Microsoft.Tye.Extensions
 {
@@ -13,6 +14,7 @@ namespace Microsoft.Tye.Extensions
         public static IReadOnlyDictionary<string, Extension> Extensions = new Dictionary<string, Extension>(StringComparer.InvariantCultureIgnoreCase)
         {
             { "dapr", new DaprExtension() },
+            { "zipkin", new ZipkinExtension() },
         };
     }
 }

src/Microsoft.Tye.Extensions/Zipkin/ZipkinExtension.cs

@@ -0,0 +1,45 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Globalization;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Microsoft.Tye.Extensions.Zipkin
+{
+    internal sealed class ZipkinExtension : Extension
+    {
+        public override string Name => "zipkin";
+
+        public override Task ProcessAsync(ExtensionContext context, ExtensionConfiguration config)
+        {
+            if (context.Application.Services.Any(s => s.Name == "zipkin"))
+            {
+                context.Output.WriteDebugLine("Zipkin service already configured. Skipping...");
+                return Task.CompletedTask;
+            }
+
+            if (context.Operation == ExtensionContext.OperationKind.LocalRun)
+            {
+                var service = new ContainerServiceBuilder("zipkin", "openzipkin/zipkin")
+                {
+                    Bindings =
+                    {
+                        new BindingBuilder()
+                        {
+                            Port = 9411,
+                            ContainerPort = 9411,
+                            Protocol = "http",
+                        },
+                    },
+                };
+                context.Application.Services.Add(service);
+            }
+
+            return Task.CompletedTask;
+        }
+    }
+}