[FIX] Accessibility work package attribute list 2258

Implements [ticket 2258](https://www.openproject.org/work_packages/2258)

:exclamation: Depends on [OpenProject Backlog PR 66](https://github.com/finnlabs/openproject-backlogs/pull/66)
:exclamation: Depends on [OpenProject Costs PR 72](https://github.com/finnlabs/openproject-costs/pull/72)