Connect the application to the registered scanner
- The variable
persistentValues/SCANNER_WIFI needs to exist, and contain the wifi name of the local scanner.
- Establishes scanner-connection
- On success: The scanner could be reached and validated
- On battery error: The scanner's battery voltage is lower than the given threshold
- On scanner error: The connection could not be established for another reason
- On wrong scanner error: The paired and the currently connected scanner are not the same
- On wifi error: The device is not connected to the scanner