Check scanner firmware

Validate whether the scanner's firmware satisfies the requirements of the current app version.

Required

• The device must be connected to the scanner

Effects

• If the firmware is up-to-date, the scanner's serial number is stored as as persistentValues/SCANNER_SERIAL, and the scanner will be disconnected
• Otherwise, the flag temp/updateNeeded is set to true, and temp/firmware is set to the update's information string

Function exits

• On success: The scanner's firmware satisfied the app's requirements
• On update needed: The scanner requires an update