Add support for DL0/Event/Trigger messages

I understand that a manual update is required for protozfits to support new message types, so I'd like to inform that the missing data model for DL0/Event/Trigger have recently been implemented and merged into master of adh-apis: https://gitlab.cta-observatory.org/cta-computing/common/acada-array-elements/adh-apis/-/merge_requests/112.