[ticket/12606] Add ACP group core events

PHPBB3-12606
Merge pull request #2518 from Pico88/ticket/12606

[ticket/12606] Add ACP group core events

* Pico88/ticket/12606:
  [ticket/12606] Add ACP group core events
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12606] Add ACP group core events