Where to setup supported sensor list

[andreondra]

1. During device configuration (add integration)
   • on inverter's fw update the device must be re-added
   • no connection to the inverter needed during integration loading (async_setup_entry should not take too long, otherwise hass wil complain)
2. During integration loading
   • no re-adding on fw update
   • very slow integration loading if the list is loaded from the inverter due to frequent timeouts from the inverter,
   • if the list can be generated without connection to the inverter (e.g. dry run of protocol parser based on cached PCU version), it will be very fast and cleaner than 1)
3. Dynamically update sensor list in coordinator
   • I don't think this is even possible

The 2) looks the best if the connection to the inverter can be avoided. For this to work, sermatec_inverter script will need to support dry-run of the protocol parser.