Freight (Carrier): Generalize CarrierJobs

[kt86]

Later it is maybe more generalized and can have 1 or to 2 locations with all the settings (LinkId, StartTimeWindow, handlingDuration).
Depending on the number of locations, the jsprit algorithm is chosen: If it is a 1-location job, jsprit uses "Services", if it has 2 locations, it uses "Shipments".

A therefore needed, central Interface is created in #3599.

Maybe something for the hackathon, or the code sprint... but definitely not urgent, but code-breaking.

(This issue was extracted from #3510.)

[kt86]

@JWJoubert @rewertvsp I have talked to Kai yesterday, and we agree, that this could make the code and would be a small improvement. But at the same time, we agreed, that this change is most-probably a "nice-to-have".
So I put in a comment in the code with that idea, but we will close the issue for the time beeing.

If you disagree, and that is something, we should really do, please reopen the issue and we can have a meeting to discuss the details :)
And/or bring it to the code-sprint in march.