Move TagHelper services to Razor.Workspaces.

- This is needed for VSCode since it does not depend on the Editor.Razor assembly. There was no reason for the TagHelper pieces to be in the Editor.Razor dll to begin with so moved them. To ensure things continue to build I type forwarded the types and left their namespaces alone.

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/DefaultTagHelperCompletionService.cs

@@ -3,15 +3,14 @@
 
 using System;
 using System.Collections.Generic;
-using System.ComponentModel.Composition;
+using System.Composition;
 using System.Diagnostics;
 using System.Linq;
 using Microsoft.AspNetCore.Razor.Language;
-using Microsoft.CodeAnalysis.Razor;
 
 namespace Microsoft.VisualStudio.Editor.Razor
 {
-    [System.Composition.Shared]
+    [Shared]
     [Export(typeof(TagHelperCompletionService))]
     internal class DefaultTagHelperCompletionService : TagHelperCompletionService
     {

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/DefaultTagHelperFactsService.cs

@@ -3,13 +3,13 @@
 
 using System;
 using System.Collections.Generic;
-using System.ComponentModel.Composition;
+using System.Composition;
 using System.Linq;
 using Microsoft.AspNetCore.Razor.Language;
 
 namespace Microsoft.VisualStudio.Editor.Razor
 {
-    [System.Composition.Shared]
+    [Shared]
     [Export(typeof(TagHelperFactsService))]
     internal class DefaultTagHelperFactsService : TagHelperFactsService
     {

src/Razor/src/Microsoft.VisualStudio.Editor.Razor/Properties/AssemblyInfo.cs

@@ -2,6 +2,8 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Runtime.CompilerServices;
+using Microsoft.VisualStudio.Editor.Razor;
+
 [assembly: InternalsVisibleTo("rzls, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("Microsoft.AspNetCore.Razor.LanguageServer.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.LiveShare.Razor, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
@@ -13,3 +15,11 @@ using System.Runtime.CompilerServices;
 [assembly: InternalsVisibleTo("Microsoft.VisualStudio.LanguageServices.Razor.Test, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("RazorDeveloperTools, PublicKey=0024000004800000940000000602000000240000525341310004000001000100f33a29044fa9d740c9b3213a93e57c84b472c84e0b8a0e1ae48e67a9f8f6de9d5f7f3d52ac23e48ac51801f1dc950abe901da34d2a9e3baadb141a17c77ef3c565dd5ee5054b91cf63bb3c6ab83f72ab3aafe93d0fc3c2348b764fafb0b1c0733de51459aeab46580384bf9d74c4e28164b7cde247f891ba07891c9d872ad2bb")]
 [assembly: InternalsVisibleTo("DynamicProxyGenAssembly2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c547cac37abd99c8db225ef2f6c8a3602f3b3606cc9891605d02baa56104f4cfc0734aa39b93bf7852f7d9266654753cc297e7d2edfe0bac1cdcf9f717241550e0a7b191195b7667bb4f64bcb8e2121380fd1d9d46ad2d92d2d15605093924cceaf74c4861eff62abf69b9291ed0a340e113be11e6a7d3113e92484cf7045cc7")]
+[assembly: TypeForwardedTo(typeof(TagHelperFactsService))]
+[assembly: TypeForwardedTo(typeof(DefaultTagHelperFactsService))]
+[assembly: TypeForwardedTo(typeof(TagHelperCompletionService))]
+[assembly: TypeForwardedTo(typeof(DefaultTagHelperCompletionService))]
+[assembly: TypeForwardedTo(typeof(AttributeCompletionContext))]
+[assembly: TypeForwardedTo(typeof(AttributeCompletionResult))]
+[assembly: TypeForwardedTo(typeof(ElementCompletionContext))]
+[assembly: TypeForwardedTo(typeof(ElementCompletionResult))]