Add power/energy metering to Samotech SM309-S

[alexjfisher]

When the device support was originally added, it was a straight copy of the SM309 code. This newer variant exposes power/energy use.

The reporting min and change parameters shamelessly cargo culted from

zigbee-herdsman-converters/devices/micromatic.js

Lines 24 to 27 in f130b98

	await reporting.rmsVoltage(endpoint, {min: 10, change: 20}); // Voltage - Min change of 2V
	await reporting.rmsCurrent(endpoint, {min: 10, change: 10}); // A - z2m displays only the first decimals, change of 10 / 0,01A
	await reporting.activePower(endpoint, {min: 10, change: 15}); // W - Min change of 1,5W
	await reporting.currentSummDelivered(endpoint, {min: 300}); // Report KWH every 5min

but they look like sensible enough settings to me.

Tested with home assistant and the zigbee2mqtt addon. Seems to work just fine.

{
    "brightness": 254,
    "linkquality": 140,
    "power_on_behavior": "previous",
    "state": "ON",
    "current": 1.15,
    "energy": 2.71,
    "power": 275.5,
    "voltage": 238.4
}

[Koenkk]

Thanks!