Use TryGetTagHelpers instead of GetTagHelpers with null check

Replace GetTagHelpers() with null check pattern with TryGetTagHelpers() for cleaner code and better null handling.

All tests pass (9/9 passing).

Co-authored-by: DustinCampbell <[email protected]>

Author: Copilot

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/CodeActions/Razor/UnboundDirectiveAttributeAddUsingCodeActionProvider.cs

@@ -93,8 +93,7 @@ private static bool TryGetMissingDirectiveAttributeNamespace(
         }
 
         // Get all tag helpers, not just those in scope, since we want to suggest adding a using
-        var tagHelpers = codeDocument.GetTagHelpers();
-        if (tagHelpers is null)
+        if (!codeDocument.TryGetTagHelpers(out var tagHelpers))
         {
             return false;
         }