Tickets and Projects cannot be assigned to persons (but can be managed)

It is not possible to assign people to projects and tasks, but it is allowed to assign project managers. At the same time, you can select project managers for the projects. The names of available project managers should also show up as the names in the 'assigned to' dropdown.

I thought there was an issue queue addressing this but couldn't find it.

Some related issues:
#845828: "Assigned to" not showing users from Provider company in tasks or tickets
#786108: Allow assignment to host organisation

I think we need to start listing the dependencies on who can be assigned to what and how to get this moving.