Xiaomi Smartmi Fresh Air System XFXTDFR02ZM support

Hi. Dear syssi added support to the library (python-miio](https://github.com/rytilahti/python-miio) XFXTDFR02ZM (zhimi.airfresh.va4).
Could you add support to core/homeassistant/components/ xiaomi_miio?

Added by @syssi you mean :slight_smile: Anyway, my understanding of the current state of xiaomi_miio integration is that there is some refactoring work to be done before any new device support can be added (it currently uses non-standard fan speeds).

Sorry, but there are no zhimi.airfresh.va4 support now.
I see changes it in airfresh.py code, but hass web-ui-intergation did not have this device in suggest.
Only zhimi.airfresh.va2.

Home Assistant 2021.11.3

Device can be added as zhimi.airfresh.va2, it comes in database as zhimi.airfresh.va4, but it has no property about air heater (ptc). So, code by @syssi are inaccessible.