Add support for entering non-hardcoded keys

[ChandlerSwift]

QR scan? Enter from app? at a minimum, allow typing.

[jrtberlin]

Cool Project!
Maybe we can add a BLE characteristic or implement a protobuf BLE characteristic.
This would allow to send more than the secret and the account name e.g. account images, account groups and tags,...
The characteristic could be implemented in Telescope and AsteroidOSSync with a QR code scanner or a parser for authenticator backups. (gnome authenticator, andOTP,... seem all to use the same format, but I haven't found a spec yet)