Use ActivationConstraint.FeatureFlag API to control when Semantic Search is enabled

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

@@ -35,19 +35,6 @@ protected override async Task InitializeAsync(CancellationToken cancellationToke
         Assumes.Present(_componentModel_doNotAccessDirectly);
     }
 
-    protected override async Task OnAfterPackageLoadedAsync(CancellationToken cancellationToken)
-    {
-        await base.OnAfterPackageLoadedAsync(cancellationToken).ConfigureAwait(false);
-
-        // TODO: remove, workaround for https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1985204
-        var globalOptions = ComponentModel.GetService<IGlobalOptionService>();
-        if (globalOptions.GetOption(SemanticSearchFeatureFlag.Enabled))
-        {
-            await JoinableTaskFactory.SwitchToMainThreadAsync(cancellationToken);
-            UIContext.FromUIContextGuid(new Guid(SemanticSearchFeatureFlag.UIContextId)).IsActive = true;
-        }
-    }
-
     protected async Task LoadComponentsInUIContextOnceSolutionFullyLoadedAsync(CancellationToken cancellationToken)
     {
         // UIContexts can be "zombied" if UIContexts aren't supported because we're in a command line build or in other scenarios.

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

@@ -371,7 +371,6 @@ 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_semantic_search_prompt", new FeatureFlagStorage("Roslyn.ShowPromptInSemanticSearch")},
         {"visual_studio_enable_copilot_rename_context", new FeatureFlagStorage("Roslyn.CopilotRenameGetContext")},
         {"visual_studio_key_binding_needs_reset", new LocalUserProfileStorage(@"Roslyn\Internal\KeybindingsStatus", "NeedsReset")},