Refactoring - Easy Top Level Structure for all sectors

[Jeniffere]

The init function of every sector should look like this:

energy consuming sectors:

production = energy_demand.calc_production(inputs)
supply = energy_source.calc_supply(inputs)

energy producing sectors:

demand = energy_demand.calc_demand(inputs)
production = energy_production.calc_production(inputs)

The implementing function code and dataclasses should be put into the subfolders:

energy consuming sectors: energy_demand, energy_source

energy producing sectors: energy_demand, energy_production

If it is necessary, you can add energy_general

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Current progress:

• agri2018
• agri2030
• business2018
• business2030
• electricity2018
• electricity2030
• fuels2018
• fuels2030
• heat2018
• heat2030
• industry2018
• industry2030
• lulucf2018
• lulucf2030
• residences2018
• residences2030
• transport2018
• transport2030
• waste2018
• waste2030