[avmfritz] add FRITZ!Smart Energy 250 - smartmeter read head

Could anyone please add the Fritz 250 smartmeter reading head, available since March '25.

Using the AIN with the Fritz 200 thing, one could at last get the “accumulated energy consumption” reading. Works maybe also for “power” and “voltage” (couldn’t try myself). Missing “battery” and “batterylow”. Couldn’t verify if the “current”, “min. power” and “max power” values are calculated or sensor readings. There is maybe also a setting for the reading period, either 10 min or 60 min.

Thanks.