Make Auteur(s) and Accès columns sortable alphabetically in admin list

app/src/Database.php

@@ -814,10 +814,12 @@ class Database
         'id'           => 't.id',
         'identifier'   => 't.identifier',
         'title'        => 't.title',
+        'authors'      => 'authors',
         'year'         => 't.year',
         'orientation'  => 'o.name',
         'ap_program'   => 'ap.code',
         'is_published' => 't.is_published',
+        'access_type'  => 'at.name',
         'submitted_at' => 't.submitted_at',
     ];