Defer to C# for component attribute GTD in cohosting

This was a subtle future bug, that we would have hit when we removed the C# syntax tree bits in future. By checking for Razor GTD first we weren't deferring to Roslyn for plain attributes (ie, the case without `@bind-` in the tests) which means at best we do some extra unnecessary work, and at worst we could lose features for things Roslyn supports but we don't.

I did not intend to find this bug when I started. Sorry for missing it in the PR Dustin. The key is that `ignoreAttributes` should have been `true` when porting over the code, and changing that would have made the test fail in your branch.

src/Razor/src/Microsoft.CodeAnalysis.Remote.Razor/GoToDefinition/RemoteGoToDefinitionService.cs

@@ -62,14 +62,6 @@ internal sealed class RemoteGoToDefinitionService(in ServiceArgs args) : RazorDo
 
         var positionInfo = GetPositionInfo(codeDocument, hostDocumentIndex);
 
-        // First, see if this is a Razor component.
-        var componentLocation = await _componentDefinitionService.GetDefinitionAsync(context.Snapshot, positionInfo, ignoreAttributes: false, cancellationToken).ConfigureAwait(false);
-        if (componentLocation is not null)
-        {
-            // Convert from VS LSP Location to Roslyn. This can be removed when Razor moves fully onto Roslyn's LSP types.
-            return Results([RoslynLspFactory.CreateLocation(componentLocation.Uri, componentLocation.Range.ToLinePositionSpan())]);
-        }
-
         if (positionInfo.LanguageKind == RazorLanguageKind.Html)
         {
             // Sometimes Html can actually be mapped to C#, like for example component attributes, which map to
@@ -83,9 +75,17 @@ internal sealed class RemoteGoToDefinitionService(in ServiceArgs args) : RazorDo
             }
         }
 
-        // If it isn't a Razor component, and it isn't C#, let the server know to delegate to HTML.
-        if (positionInfo.LanguageKind != RazorLanguageKind.CSharp)
+        if (positionInfo.LanguageKind is RazorLanguageKind.Html or RazorLanguageKind.Razor)
         {
+            // First, see if this is a Razor component. We ignore attributes here, because they're better served by the C# handler.
+            var componentLocation = await _componentDefinitionService.GetDefinitionAsync(context.Snapshot, positionInfo, ignoreAttributes: true, cancellationToken).ConfigureAwait(false);
+            if (componentLocation is not null)
+            {
+                // Convert from VS LSP Location to Roslyn. This can be removed when Razor moves fully onto Roslyn's LSP types.
+                return Results([RoslynLspFactory.CreateLocation(componentLocation.Uri, componentLocation.Range.ToLinePositionSpan())]);
+            }
+
+            // If it isn't a Razor component, and it isn't C#, let the server know to delegate to HTML.
             return CallHtml;
         }