Add support for zhimi.airpurifier.v3

[0x5e]

PS: The zhimi.airpurifier.v3 product name is not v3, it's just first version of Xiaomi Mi Air Purifier.

However there's a known issue for this device: fan level polling failed. If anyone knows how to solve it, please have a try. Error while parsing response from device for property air-purifier:fan-level. Response: {"did":"686324","siid":2,"piid":2,"code":-704220043,"exe_time":0}

[merdok]

I think that the error code 704220043 indicates that the property value is not within the value range defined by miot. But that is strange since you are getting that during polling.

[merdok]

Other then that, the pull request looks good! Thanks!

[0x5e]

Yeah, strange, I guess this device's official spec is not correct, when I switch to the auto/sleep mode, the fan level changed into the unknown value that was not included in the low/medium/high. Then the poll api got failed.