[Cervantes, Kobo] Stricter WiFi callback (#4616)
[Cervantes, Kobo] Stricter WiFi callback (#4616)

* Double-checks that the connection was successful, and forcefully kills WiFi if it didn't, to avoid leaving stuff in an inconsistent state.

Should fix #2183

* Limit the turnOffWifi call to devices where it might make some sense to
do
Frenzie/koreader,mwoz123/koreader,koreader/koreader,NiLuJe/koreader,pazos/koreader,Frenzie/koreader,koreader/koreader,Markismus/koreader,NiLuJe/koreader,mihailim/koreader,Hzj-jie/koreader,poire-z/koreader,poire-z/koreader,houqp/koreader