fs,win: do not add a second trailing slash in readdir

Do not add a trailing slash if it was not removed by resolve in
ToNamespacedPath.

PR-URL: #59847
Fixes: #58223
Refs: #56110
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Stefan Stojanovic <stefan.stojanovic@janeasystems.com>

Author: Flarna

src/node_file.cc

@@ -1994,7 +1994,7 @@ static void ReadDir(const FunctionCallbackInfo<Value>& args) {
   ToNamespacedPath(env, &path);
 
 #ifdef _WIN32
-  if (slashCheck) {
+  if (slashCheck && !path.ToStringView().ends_with("\\")) {
     size_t new_length = path.length() + 1;
     path.AllocateSufficientStorage(new_length + 1);
     path.SetLengthAndZeroTerminate(new_length);