Allow querying volumes as a nested field of departments
In order to allow the frontend application to load all departments together with their volumes in a single query as it is desired for the new departments overview page, the schema of the Department
type of the API should be extended by an additional field volumes
that loads the list of all volumes of a department.
As always, the implementation of this sub-field should make use of dataloader
in order to reduce the number of queries and increase the efficiency.