ZONE_CHANGE_GROUP event must be reworked to fix duplicated events

From https://github.com/magefree/mage/issues/7572#issuecomment-875969895

Group event (`ZONE_CHANGE_GROUP`) introduced long ago for triggers like `whenever one or more cards` (example: [[The Gitrog Monster]]). E.g. you must catch only one event at the end and trigger on it. ~13 cards uses it.

Current grouping code splits events by zones/source/player (see `ZoneChangeData`), e.g. it creates multiple group events instead one. It can be potentially buggy for some some use cases.

Possible solution: do not split events by multiple groups. Use one group instead. And keep all necessary information (cards/tokens list, map between card and original event).