Author: Sara Arjona
MDL-69002 core_badges: add methods to support backpack validation
A more generic method has been added to the API to validate the
backpack connection (for now, there was only one method for
validating current backpack).
Besides, a renderer has been added to display this information
depending on the backpackid.
+ 3.8 en [backpackconnectionok,core_badges]
+ 3.8 en [backpackconnectionnottested,core_badges]
+ 3.8 en [testbackpack,core_badges]