Bestelbon overzicht: show Consultant, and Klant columns instead of Project Code

[heynist]

The Consultant is to be fetched from the Akkoord, and the Klant from the Akkoord-->Opdracht relations.
Make both columns hyperlinks to the respective entities.

Preferably the ordering is on the first column Consultant, then second column Klant and then on the third column StartDatum.

The existing Project Code column should disappear. It is currently also hyperlinking to the wrong entity as well (Business Units), but no need to fix this anymore, just remove the column altogether.