MDL-67115 core: php74 params order for implode()/join()

Passing parameters to implode() in reverse order is deprecated, use
implode($glue, $parts) instead of implode($parts, $glue).

This commit corresponds to phpunit and manual detections, core files.

question/editlib.php

@@ -490,7 +490,7 @@ function question_build_edit_resources($edittab, $baseurl, $params) {
     foreach ($contexts->having_one_edit_tab_cap($edittab) as $context){
         $contextlistarr[] = "'{$context->id}'";
     }
-    $contextlist = join($contextlistarr, ' ,');
+    $contextlist = join(' ,', $contextlistarr);
     if (!empty($pagevars['cat'])){
         $catparts = explode(',', $pagevars['cat']);
         if (!$catparts[0] || (false !== array_search($catparts[1], $contextlistarr)) ||