Add Viomi Smart AC A1-18K

[EdgeLord03]

Device information:

• Name(s) of the device: Smart AC A1-18K

• Link: https://www.bdstall.com/details/xiaomi-viomi-a1-15-ton-split-smart-ac-72354/

• Model: viomi.aircondition.y89

• Hardware version: esp32

• Firmware version: 2.2.7

The AC can be turned on and off using genericmiot, some functions like the eco mode work, too. However, it does say that it's an unsupported model, thus this issue. Also this AC only appears on the Mi Home app if used under Mainland China.

First time on GitHub, please be sure to guide me if I make any mistake/do anything wrong, thank you!