backend, frontends: callbacks refactoring:

- launchAction is now async, and return a dictionary for its result
    - no more action_id, actionResult* are deprecated
    - callback system is about to be unified

src/plugins/plugin_misc_quiz.py

@@ -26,8 +26,6 @@ from twisted.words.protocols.jabber.xmlstream import IQ
 import random
 
 from wokkel import data_form
-from sat.tools.xml_tools import dataForm2XML
-from sat_frontends.tools.games import TarotCard
 from time import time