Extended conditions for event handlers

[h-meier]

It would be very useful to have the possibility to add extended conditions to event handlers, too. Some use cases are not possible without setting such conditions for the events. E.g: Send an e-mail to a user if he enrolls another token from an already existing token type.

[nilsbehlen]

#4190

[jelinaunger]

TODO:

• Add columns to EventHandlerCondition (DB):
  • section (see PolicyCondition)
  • active (see PolicyCondition)
  • handle_missing_data (see PolicyCondition)
  • extended_condition (bool): to easily differentiate between the "hard coded" conditions and the extended ones
• check_condition()
  • extract extended conditions to handle them differently
• generalize PolicyConditionClass and apply the condition matching to the extended conditions in check_condition()
• Add extended group