MDL-27171 lib/moodlelib: change the order of plugins returned by get_plugin_types function

We need to ensure that message/output is installed first so that default
messaging settings are set correctly afterwards.

Signed-off-by: Ruslan Kabalin <ruslan.kabalin@luns.net.uk>

lib/moodlelib.php

@@ -7067,10 +7067,12 @@ function get_plugin_types($fullpaths=true) {
     static $fullinfo = null;
 
     if (!$info) {
-        $info = array('mod'           => 'mod',
+        // BEWARE: message/output should always be the first as we need to have
+        // message outputs installed before installing every other plugin.
+        $info = array('message'       => 'message/output',
+                      'mod'           => 'mod',
                       'auth'          => 'auth',
                       'enrol'         => 'enrol',
-                      'message'       => 'message/output',
                       'block'         => 'blocks',
                       'filter'        => 'filter',
                       'editor'        => 'lib/editor',