[14.0][FIX]operating_unit: show only user-readable operating units

[PicchiSeba]

In a multi-company environment there might be cases where our user is in the operating_unit.group_manager_operating_unit group and is trying to see another user's form view. If the other user has been assigned to some Operating Units owned by another company, opening the view results in an access error because we don't have access to the other company's data.

With this PR we handle this case, filtering out all those OU we cannot access