[ticket/12930] core.ucp_pm_compose_compose_pm_quotepost_query_after

Adding the core.ucp_pm_compose_compose_pm_quotepost_query_after
event to ucp backend.

https://tracker.phpbb.com/browse/PHPBB3-12930

PHPBB3-12930
Should just be `core.ucp_pm_compose_quotepost_query_after`