Fix VS xaml lsp shutdown (#78304)

was refactored in the extensions work, and we missed adding an export
for the VS xaml server

resolves https://devdiv.visualstudio.com/DevDiv/_workitems/edit/2456006

Author: dibarbet

src/VisualStudio/Xaml/Impl/Implementation/LanguageServer/XamlLifeCycleManager.cs

@@ -0,0 +1,17 @@
+// 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.Composition;
+using Microsoft.CodeAnalysis.Editor.Xaml;
+using Microsoft.CodeAnalysis.Host.Mef;
+using Microsoft.CodeAnalysis.LanguageServer;
+using Microsoft.CodeAnalysis.LanguageServer.Handler.ServerLifetime;
+
+namespace Microsoft.VisualStudio.LanguageServices.Xaml.LanguageServer;
+
+[ExportLspServiceFactory(typeof(LspServiceLifeCycleManager), StringConstants.XamlLspLanguagesContract), Shared]
+[method: ImportingConstructor]
+[method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
+internal sealed class XamlLifeCycleManager(LspWorkspaceRegistrationService lspWorkspaceRegistrationService) : LspServiceLifeCycleManager.LspLifeCycleManagerFactory(lspWorkspaceRegistrationService);