Refactor "Blocking Deletion of Warehouse Shipment Lines" example to unit tests

[lvanvugt]

WIth the ATDD (including Test Plan (TP)) approach we tests the full scenarios that include all kind of data setup prerequisites. This is time consuming, both in designing, building and executing. As Vjeko showed in various sessions on Days of Knowledge and BC TechDays, we could make it all more efficient by wrinting testable code allowing to test purely the business logic. In this way we can buid better code - in units - and (unit) test more efficient .

@CNAPilaro and I are investigating how the ATDD/TP approach can be combined with Vjeko's approach. The result might get presented at Direction EMEA 2023, and the code will be stroed in the branch DirectionsEMA2023.