Support for push status updates in Yeelight integration

Currently Yeelight integration seems to support only local polling as a mean of lights status updates, this leads to delays of up to 30 sec in updating the light status in case it was changed from outside of HA.

Yeelights LAN control protocol supports lights status push to all connected devices, per protocol description in the paragraph 4.3 “Notification message” (available here: Developer Mode Yeelight).

Would be great to have this status push support implemented, with polling method remaining as a fallback.