Keep the message the same as :enoent for Windows compat

Author: sabiwara

lib/iex/lib/iex/helpers.ex

@@ -1084,7 +1084,7 @@ defmodule IEx.Helpers do
         if File.exists?(path) do
           IO.puts(IEx.color(:eval_info, Path.absname(path)))
         else
-          IO.puts(IEx.color(:eval_error, "Not a directory #{path}"))
+          IO.puts(IEx.color(:eval_error, "No such file or directory #{path}"))
         end
 
       {:error, reason} ->

lib/iex/test/iex/helpers_test.exs

@@ -1219,7 +1219,7 @@ defmodule IEx.HelpersTest do
         path = Path.join("mix.exs", "foo")
 
         assert capture_io(fn -> ls(path) end) ==
-                 "Not a directory #{path}\n"
+                 "No such file or directory #{path}\n"
       end)
     end
   end