WebAPI: Added support for Wallbox charging power (apparent)

WebAPI: Add Sensor for Wallbox (apparent) ChargingPower

Add support for wallbox charging power (I-IV) for WebAPI integration (when this data is not available via local SENEC integration (like for P4 owners) See #215 for details. Please note, that the new sensors are disabled by default (so if you want to use them, you must manually activate them first)

Please consider supporting me

Thanks to those who have already supported me in the past weeks or month that is highly appreciated! To the other users: I am putting quite an amount of energy and passion into this integration. Perhaps you could give yourself a little push (if you can afford it) and become a sponsor.

If you haven't starred this integration in Github yet - please do so - TIA