MDL-67063 h5p: new h5plib plugintype for supporting multi coreAPI

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.

lib/classes/plugin_manager.php

@@ -1881,6 +1881,10 @@ class core_plugin_manager {
                 'rubric', 'guide'
             ),
 
+            'h5plib' => array(
+                'v124'
+            ),
+
             'local' => array(
             ),