MDL-58713 filters: Support auto-loading in the filters component

lib/classes/component.php

@@ -443,7 +443,7 @@ $cache = '.var_export($cache, true).';
             'filepicker'  => null,
             'fileconverter' => $CFG->dirroot.'/files/converter',
             'files'       => $CFG->dirroot.'/files',
-            'filters'     => null,
+            'filters'     => $CFG->dirroot.'/filter',
             //'fonts'       => null, // Bogus.
             'form'        => $CFG->dirroot.'/lib/form',
             'grades'      => $CFG->dirroot.'/grade',