Fix login/password encoding and bookmark logins

Heya, this is my first time touching a Swift project so I'm not sure if this is a reasonable solution, but this PR fixes two problems for me: 1. logging in with a non-default user/pass from the Connect to Server window 2. logging in with non-default user, or pass from a saved bookmark For the login/pass string encoding, it seems like `stringInput.data(using: encoding, allowLossyConversion: true)` was producing the wrong bytes in some way I couldn't understand, so switched up to using `[UInt8]` and that seemed to work. I hope this helps and thanks for your work on this.