[Request] Make Solarcharger integration more generic

[AndreasBoehm]

Is your feature request related to a problem? Please describe.

Multiple people requested to feed solarcharger data via MQTT and the first step to make that possible is to make the solarcharger integration more generic. This will also make it easier to integrate solarchargers from different brands in the future.

Describe the solution you'd like

• Rename 'VE.Direct' to 'Solarcharger' in translations everywhere where its not about Victron specific settings
• Rename classes that are not Victron specific
• Add 'Provider' dropdown on 'Solarcharger' admin page that contains 'VE.Direct' as the only option
• Create generic Solarcharger-Provider integration with a separate VE.Direct implementation

Describe alternatives you've considered

No response

Additional context

#457