Let implemented harvest settings inherit from base harvest settings

[sdruskat]

When creating a UML class model to show an exemplary plugin implementation, I stumbled over this:

hermes/src/hermes/commands/harvest/cff.py

Line 30 in d3f4656

class CffHarvestSettings(BaseModel):

I believe that this should really be

from hermes.commands.harvest.base import HarvestSettings

class CffHarvestSettings(HarvestSettings): 
    ...

@led02 & @SKernchen: correct?

[sdruskat]

No, settings should inherit directly from BaseModel so as to not pull in settings from other levels (workflow, command step). See #302 (comment).