SDLSorter fixes (#329)

Author: Shane32

src/GraphQLParser/Visitors/SDLSorter.cs

@@ -19,7 +19,7 @@ private SDLSorter()
     /// </summary>
     public static void Sort(ASTNode node, SDLSorterOptions? options = null)
 #pragma warning disable CA2012 // Use ValueTasks correctly
-        => _ = _sorter.VisitAsync(node, options ?? SDLSorterOptions.Default);
+        => _sorter.VisitAsync(node, options ?? SDLSorterOptions.Default).GetAwaiter().GetResult();
 #pragma warning restore CA2012 // Use ValueTasks correctly
 
     /// <inheritdoc/>

src/GraphQLParser/Visitors/SDLSorterOptions.cs

@@ -69,7 +69,7 @@ public virtual int Compare(ASTNode x, ASTNode y)
 
     /// <inheritdoc/>
     public int Compare(DirectiveLocation x, DirectiveLocation y)
-        => Comparer<string>.Default.Compare(x.ToString(), y.ToString());
+        => string.Compare(x.ToString(), y.ToString(), StringComparison);
 
     int IComparer<ASTNode>.Compare(ASTNode? x, ASTNode? y) => Compare(x!, y!);
 }