Port document color endpoints to cohosting in VS Code (#11775)

Part of #11759

Razor side of dotnet/vscode-csharp#8210

This PR does the infra for html requests in cohosting, and ports
document color as the first test case. It's extremely simple after the
re-layering PR from the other day :)

Author: davidwengier

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/LanguageClient/Cohost/CohostColorPresentationEndpoint.cs renamed to src/Razor/src/Microsoft.CodeAnalysis.Razor.CohostingShared/DocumentColor/CohostColorPresentationEndpoint.cs

@@ -7,13 +7,14 @@
 using Microsoft.AspNetCore.Razor;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.ExternalAccess.Razor.Cohost;
+using Microsoft.CodeAnalysis.ExternalAccess.Razor.Features;
 
 namespace Microsoft.VisualStudio.Razor.LanguageClient.Cohost;
 
 #pragma warning disable RS0030 // Do not use banned APIs
 [Shared]
 [CohostEndpoint(Methods.TextDocumentColorPresentationName)]
-[ExportCohostStatelessLspService(typeof(CohostColorPresentationEndpoint))]
+[ExportRazorStatelessLspService(typeof(CohostColorPresentationEndpoint))]
 [method: ImportingConstructor]
 #pragma warning restore RS0030 // Do not use banned APIs
 internal sealed class CohostColorPresentationEndpoint(

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/LanguageClient/Cohost/CohostDocumentColorEndpoint.cs renamed to src/Razor/src/Microsoft.CodeAnalysis.Razor.CohostingShared/DocumentColor/CohostDocumentColorEndpoint.cs

@@ -8,14 +8,15 @@
 using Microsoft.AspNetCore.Razor;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.ExternalAccess.Razor.Cohost;
+using Microsoft.CodeAnalysis.ExternalAccess.Razor.Features;
 
 namespace Microsoft.VisualStudio.Razor.LanguageClient.Cohost;
 
 #pragma warning disable RS0030 // Do not use banned APIs
 [Shared]
 [CohostEndpoint(Methods.TextDocumentDocumentColorName)]
 [Export(typeof(IDynamicRegistrationProvider))]
-[ExportCohostStatelessLspService(typeof(CohostDocumentColorEndpoint))]
+[ExportRazorStatelessLspService(typeof(CohostDocumentColorEndpoint))]
 [method: ImportingConstructor]
 #pragma warning restore RS0030 // Do not use banned APIs
 internal sealed class CohostDocumentColorEndpoint(
@@ -30,16 +31,11 @@ internal sealed class CohostDocumentColorEndpoint(
 
     public ImmutableArray<Registration> GetRegistrations(VSInternalClientCapabilities clientCapabilities, RazorCohostRequestContext requestContext)
     {
-        if (clientCapabilities.SupportsVisualStudioExtensions)
+        return [new Registration
         {
-            return [new Registration
-            {
-                Method = Methods.TextDocumentDocumentColorName,
-                RegisterOptions = new DocumentColorRegistrationOptions()
-            }];
-        }
-
-        return [];
+            Method = Methods.TextDocumentDocumentColorName,
+            RegisterOptions = new DocumentColorRegistrationOptions()
+        }];
     }
 
     protected override RazorTextDocumentIdentifier? GetRazorTextDocumentIdentifier(DocumentColorParams request)

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/LanguageClient/Cohost/HtmlDocumentSynchronizer.RazorDocumentVersion.cs renamed to src/Razor/src/Microsoft.CodeAnalysis.Razor.CohostingShared/HtmlDocumentServices/HtmlDocumentSynchronizer.RazorDocumentVersion.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Razor;
 using Microsoft.CodeAnalysis;
 
 namespace Microsoft.VisualStudio.Razor.LanguageClient.Cohost;
@@ -33,7 +34,7 @@ private void Start(TextDocument document, Func<TextDocument, CancellationToken,
             _cts.Token.Register(Dispose);
             _ = syncFunction.Invoke(document, _cts.Token).ContinueWith((t, state) =>
             {
-                var tcs = (TaskCompletionSource<bool>)state;
+                var tcs = (TaskCompletionSource<bool>)state.AssumeNotNull();
                 if (t.IsCanceled)
                 {
                     tcs.SetResult(false);

src/Razor/src/Microsoft.VisualStudio.LanguageServices.Razor/LanguageClient/Cohost/HtmlDocumentSynchronizer.SynchronizationRequest.cs renamed to src/Razor/src/Microsoft.CodeAnalysis.Razor.CohostingShared/HtmlDocumentServices/HtmlDocumentSynchronizer.SynchronizationRequest.cs

@@ -12,7 +12,16 @@
     <Compile Include="$(MSBuildThisFileDirectory)CohostEndpointAttribute.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)CohostDocSyncEndpointRegistration.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)CohostStartupService.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)DocumentColor\CohostColorPresentationEndpoint.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)DocumentColor\CohostDocumentColorEndpoint.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)DocumentSymbol\CohostDocumentSymbolEndpoint.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)HtmlDocumentServices\HtmlDocumentSynchronizer.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)HtmlDocumentServices\HtmlDocumentSynchronizer.RazorDocumentVersion.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)HtmlDocumentServices\HtmlDocumentSynchronizer.SynchronizationRequest.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)HtmlDocumentServices\IHtmlDocumentPublisher.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)HtmlDocumentServices\IHtmlDocumentSynchronizer.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)HtmlDocumentServices\HtmlRequestInvokerExtensions.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)HtmlDocumentServices\IHtmlRequestInvoker.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)InlayHints\CohostInlayHintEndpoint.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)InlayHints\CohostInlayHintResolveEndpoint.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)IRazorCohostStartupService.cs" />