Add support in Vesync for Levoit 400s Air Purifier

I’m working on updating this integration (on the shoulders of others). Currently it (hopefully) works for all humidifiers, but a similar fix will be needed for the fans so all models in the library work with HA. I don’t have a fan so to do it, I’d need a tester (or 2).

I have a test repo and created a new topic. VeSync development particularly for Levoit Humdifiers