Issue741 movedatabasecode

[HansVRP]

first proposal to seperate the job database/dataframe logic and the processbasedjobstart

[HansVRP]

TODO; move also the unit tests once settled on rearangement

[soxofaan]

I'd try to do this exercise in atomic commits/PRs:

• avoid moving unrelated things at the same time (like JobDatabaseInterface and ProcessBasedJobCreator here)
• move related things in same commit: e.g. if you move ProcessBasedJobCreator, also move tests and update docs in same commit (or at least same PR)

that will avoid long-running PR review cycles that block other progress

e.g. I just started #824 to only move ProcessBasedJobCreator