The joubel/core and joubel/editor libraries have been moved to Moodle
namespace.
This commit adds the new namespace to the places where these classes
are used.
Besides, a couple of minor changes have been done to replace the _test.php
classname and remove some unnecessary defined('MOODLE_INTERNAL').
A new plugintype has been created for having more than one installed
third-party H5P libraries. Existing libraries have been moved from
lib/h5p to the new h5plib_v124 plugin.
Sara Arjona