Move extension method out of Microsoft.AspNetCore (#11148)

* Move extension method out of Microsoft.AspNetCore

* Empty commit

Author: javiercn

src/Hosting/Hosting/ref/Microsoft.AspNetCore.Hosting.netcoreapp3.0.cs

@@ -1,13 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-namespace Microsoft.AspNetCore
-{
-    public static partial class StaticWebAssetsWebHostBuilderExtensions
-    {
-        public static Microsoft.AspNetCore.Hosting.IWebHostBuilder UseStaticWebAssets(this Microsoft.AspNetCore.Hosting.IWebHostBuilder builder) { throw null; }
-    }
-}
 namespace Microsoft.AspNetCore.Hosting
 {
     public partial class DelegateStartup : Microsoft.AspNetCore.Hosting.StartupBase<Microsoft.Extensions.DependencyInjection.IServiceCollection>
@@ -29,6 +22,10 @@ public StartupBase(Microsoft.Extensions.DependencyInjection.IServiceProviderFact
         public virtual void ConfigureContainer(TBuilder builder) { }
         public override System.IServiceProvider CreateServiceProvider(Microsoft.Extensions.DependencyInjection.IServiceCollection services) { throw null; }
     }
+    public static partial class StaticWebAssetsWebHostBuilderExtensions
+    {
+        public static Microsoft.AspNetCore.Hosting.IWebHostBuilder UseStaticWebAssets(this Microsoft.AspNetCore.Hosting.IWebHostBuilder builder) { throw null; }
+    }
     public partial class WebHostBuilder : Microsoft.AspNetCore.Hosting.IWebHostBuilder
     {
         public WebHostBuilder() { }

src/Hosting/Hosting/src/StaticWebAssets/StaticWebAssetsWebHostBuilderExtensions.cs

@@ -4,7 +4,7 @@
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Hosting.StaticWebAssets;
 
-namespace Microsoft.AspNetCore
+namespace Microsoft.AspNetCore.Hosting
 {
     /// <summary>
     /// Extensions for configuring static web assets for development.