adjust the initial capacity to the typical number of suggestions

Author: h3xds1nz

src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Documents/Speller.cs

@@ -186,7 +186,7 @@ internal List<string> GetSuggestionsForError(SpellingError error)
             // calculate the exact same error.  Keep the two methods in sync!
             //
 
-            List<string> suggestions = new();
+            List<string> suggestions = new(4);
             CultureInfo culture = GetCurrentCultureAndLanguage(error.Start, out XmlLanguage language);
 
             if (culture is not null || _spellerInterop.CanSpellCheck(culture))