[WO-786] Select inbox after onConnect

* pre-select inbox in imap in onConnect (avoids race condition with listening imap connection)
* select inbox in UI after onConnect was successful
* connecting listening client successfully no longer important for the outcome of onConnect
uid is not always of type 'string' ... sometimes it's of type 'number'. That's why I parsed only conditionally. Have you tested if this works in all cases?