Feature request: allow flow rules based on participation tags

When granting exceptions to a group of students, we can apply those tags instead of granting exceptions to participations one by one.

I think there can be two type of rules to be added: ``if_has_participation_tagged_any`` and ``if_has_participation_tagged_all``, both of which require a list, with the former match any, while the latter requiring a inclusive match (``participation.tags`` >= ``rules.if_has_participation_tagged_all``).