Support multiple devices in config

[stuertz]

Is your feature request related to a problem? Please describe.
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I'm having two devices in Solarman registered (2 PV Panels each with its own inverter, logger, etc)

Describe the solution you'd like
Do I understand it correctly that i currently can only run two instances of this project to fetch both devices?
Wouldn't it be better to have a list of devices configurable in config.json

Describe alternatives you've considered
Running multiple instances, each per device