Use ActivationConstraint.FeatureFlag API to control when Semantic Search is enabled (#77133)

Author: tmat

src/VisualStudio/CSharp/Impl/SemanticSearch/OpenSemanticSearchWindowCommand.cs

@@ -2,7 +2,6 @@
 // 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.Threading;
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.Extensibility;
@@ -20,7 +19,7 @@ internal sealed class OpenSemanticSearchWindowCommand : Command
     {
         Icon = new(ImageMoniker.KnownValues.FindSymbol, IconSettings.IconAndText),
         Placements = [CommandPlacement.KnownPlacements.ViewOtherWindowsMenu.WithPriority(0x8010)],
-        VisibleWhen = ActivationConstraint.UIContext(Guid.Parse(SemanticSearchFeatureFlag.UIContextId))
+        VisibleWhen = ActivationConstraint.FeatureFlag("Roslyn.SemanticSearchEnabled")
     };
 
     public override Task ExecuteCommandAsync(IClientContext context, CancellationToken cancellationToken)

src/VisualStudio/Core/Def/LanguageService/AbstractPackage.cs

@@ -70,26 +70,6 @@ async Task EnsureComponentModelAsync(PackageLoadTasks packageInitializationTasks
 
     protected virtual void RegisterOnAfterPackageLoadedAsyncWork(PackageLoadTasks afterPackageLoadedTasks)
     {
-        afterPackageLoadedTasks.AddTask(
-            isMainThreadTask: false,
-            task: (afterPackageLoadedTasks, cancellationToken) =>
-            {
-                // TODO: remove, workaround for https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1985204
-                var globalOptions = ComponentModel.GetService<IGlobalOptionService>();
-                if (globalOptions.GetOption(SemanticSearchFeatureFlag.Enabled))
-                {
-                    afterPackageLoadedTasks.AddTask(
-                        isMainThreadTask: true,
-                        task: (packageLoadedTasks, cancellationToken) =>
-                        {
-                            UIContext.FromUIContextGuid(new Guid(SemanticSearchFeatureFlag.UIContextId)).IsActive = true;
-
-                            return Task.CompletedTask;
-                        });
-                }
-
-                return Task.CompletedTask;
-            });
     }
 
     protected async Task LoadComponentsInUIContextOnceSolutionFullyLoadedAsync(CancellationToken cancellationToken)

src/VisualStudio/Core/Def/Options/VisualStudioOptionStorage.cs

@@ -367,7 +367,6 @@ public bool TryFetch(LocalUserRegistryOptionPersister persister, OptionKey2 opti
         {"dotnet_highlight_related_json_components", new RoamingProfileStorage("TextEditor.%LANGUAGE%.Specific.HighlightRelatedJsonComponentsUnderCursor")},
         {"dotnet_unsupported_report_invalid_json_patterns", new RoamingProfileStorage("TextEditor.%LANGUAGE%.Specific.ReportInvalidJsonPatterns")},
         {"visual_studio_enable_key_binding_reset", new FeatureFlagStorage("Roslyn.KeybindingResetEnabled")},
-        {"visual_studio_enable_semantic_search", new FeatureFlagStorage("Roslyn.SemanticSearchEnabled")},
         {"visual_studio_enable_copilot_rename_context", new FeatureFlagStorage("Roslyn.CopilotRenameGetContext")},
         {"visual_studio_key_binding_needs_reset", new LocalUserProfileStorage(@"Roslyn\Internal\KeybindingsStatus", "NeedsReset")},
         {"visual_studio_key_binding_reset_never_show_again", new LocalUserProfileStorage(@"Roslyn\Internal\KeybindingsStatus", "NeverShowAgain")},