Only show command when in context of git repo

Since `Open from clipboard` requires a repository to navigate, we only
want to advertise the command when in the context of a repository.

Author: jcansdale

src/GitHub.VisualStudio/Commands/OpenFromClipboardCommand.cs

@@ -4,6 +4,7 @@
 using GitHub.Exports;
 using GitHub.Services;
 using GitHub.Services.Vssdk.Commands;
+using Microsoft.VisualStudio.Shell;
 using Task = System.Threading.Tasks.Task;
 
 namespace GitHub.VisualStudio.Commands
@@ -22,6 +23,7 @@ public class OpenFromClipboardCommand : VsCommand<string>, IOpenFromClipboardCom
         readonly Lazy<IGitHubContextService> gitHubContextService;
         readonly Lazy<ITeamExplorerContext> teamExplorerContext;
         readonly Lazy<IVSServices> vsServices;
+        readonly UIContext uiContext;
 
         /// <summary>
         /// Gets the GUID of the group the command belongs to.
@@ -46,6 +48,9 @@ public OpenFromClipboardCommand(
 
             // See https://code.msdn.microsoft.com/windowsdesktop/AllowParams-2005-9442298f
             ParametersDescription = "u";    // accept a single url
+
+            // This command is only visible when in the context of a Git repository
+            uiContext = UIContext.FromUIContextGuid(new Guid(Guids.UIContext_Git));
         }
 
         public override async Task Execute(string url)
@@ -109,5 +114,10 @@ public override async Task Execute(string url)
 
             gitHubContextService.Value.TryOpenFile(repositoryDir, context);
         }
+
+        protected override void QueryStatus()
+        {
+            Visible = uiContext.IsActive;
+        }
     }
 }

src/GitHub.VisualStudio/GitHub.VisualStudio.vsct

@@ -127,6 +127,8 @@
         <Icon guid="guidImages" id="logo" />
         <CommandFlag>IconIsMoniker</CommandFlag>
         <CommandFlag>AllowParams</CommandFlag>
+        <CommandFlag>DefaultInvisible</CommandFlag>
+        <CommandFlag>DynamicVisibility</CommandFlag>
         <Strings>
           <ButtonText>Open from clipboard</ButtonText>
           <CanonicalName>.GitHub.OpenFromClipboard</CanonicalName>