Simplify access logic for computed referenced projects via query access

[simonbaese]

Access to project entities is determined in ProjectEntityAccess. For computed referenced projects the relation is determined via an entity query which does not respect the access control handler. At the moment, while computing referenced projects, all projects are queried with a subsequent access check - which requires loading the projects again (see ComputedProjectReferenceFieldItemList).

The access check should already happen during the query. The architecture of the project entity is already prepared and the event subscriber (provided by the entity module) can be found as ProjectQueryAccessSubscriber.

Building the queries might be very tricky though, because one has to respect the current status of the project and the role of the user in relation to the project. Also, there should be some mechanism to mirror the entity access check mentioned in the beginning.