`prompter:active-attributes-keys` must not depend on the order of the arguments

[André A. Gomes]

Noticed when working on #3362. Steps to reproduce below.

Nyxt @ 9fb9036

Patched

modified   source/mode/file-manager.lisp
@@ -166,7 +166,7 @@ defun make-file-source-preprocessor
 (define-class file-source (prompter:source)
   ((prompter:name "Files")
    (prompter:active-attributes-keys
-    '("Name" "Extension" "Directory")
+    '("Extension" "Name" "Directory")
     :accessor nil)
    (prompter:filter-preprocessor (make-file-source-preprocessor))
    (prompter:enable-marks-p t)