Add implicit DI feature for out-of-proc worker (Azure#523)

Author: justinyoo

samples/Microsoft.Azure.Functions.Worker.Extensions.OpenApi.FunctionApp.OutOfProc/Program.cs

@@ -19,7 +19,6 @@ public static void Main()
         {
             var host = new HostBuilder()
                 .ConfigureFunctionsWorkerDefaults(worker => worker.UseNewtonsoftJson())
-                .ConfigureOpenApi()
                 .ConfigureServices(services =>
                 {
                     services.AddSingleton<Fixture>(new Fixture())

src/Microsoft.Azure.Functions.Worker.Extensions.OpenApi/OpenApiWorkerStartup.cs

@@ -0,0 +1,24 @@
+using Microsoft.Azure.Functions.Worker.Core;
+using Microsoft.Azure.Functions.Worker.Extensions.OpenApi;
+using Microsoft.Azure.Functions.Worker.Extensions.OpenApi.Functions;
+using Microsoft.Azure.WebJobs.Extensions.OpenApi.Core.Abstractions;
+using Microsoft.Extensions.DependencyInjection;
+
+[assembly: WorkerExtensionStartup(typeof(OpenApiWorkerStartup))]
+
+namespace Microsoft.Azure.Functions.Worker.Extensions.OpenApi
+{
+    /// <summary>
+    /// This represents the startup entity for OpenAPI endpoints registration
+    /// </summary>
+    public class OpenApiWorkerStartup : WorkerExtensionStartup
+    {
+        /// <inheritdoc />
+        public override void Configure(IFunctionsWorkerApplicationBuilder applicationBuilder)
+        {
+            applicationBuilder.Services.AddSingleton<IOpenApiHttpTriggerContext, OpenApiHttpTriggerContext>();
+            applicationBuilder.Services.AddSingleton<IOpenApiTriggerFunction, OpenApiTriggerFunction>();
+            //applicationBuilder.Services.AddSingleton<DefaultOpenApiHttpTrigger, DefaultOpenApiHttpTrigger>();
+        }
+    }
+}