MDL-33409 Newly copied files should take on the userid of the current user, and dates reset

- changed function repository::copy_to_area so it accepts more file attributes, pass changed attributes to it
- changed file_info::copy_to_storage and file_info_stored::copy_to_storage to accept more file attributes
- simplified file size check for moodle files in repository/repository_ajax.php
- removed unused code in repository/repository_ajax.php

lib/filebrowser/file_info.php

@@ -303,15 +303,11 @@ abstract class file_info {
     /**
      * Copy content of this file to local storage, overriding current file if needed.
      *
-     * @param int $contextid context ID
-     * @param string $component component
-     * @param string $filearea file area
-     * @param int $itemid item ID
-     * @param string $filepath file path
-     * @param string $filename file name
-     * @return boolean success
+     * @param array|stdClass $filerecord contains contextid, component, filearea,
+     *    itemid, filepath, filename and optionally other attributes of the new file
+     * @return bool success
      */
-    public function copy_to_storage($contextid, $component, $filearea, $itemid, $filepath, $filename) {
+    public function copy_to_storage($filerecord) {
         return false;
     }