registerLastDeviceRecoveryKey
suspend fun registerLastDeviceRecoveryKey(device: AuthenticatedDevice, registration: LastDeviceRecoveryKeyRegistration): Boolean
Registers registration's public key as the last-device recovery key of the authenticated device's user (docs/last-device-recovery.md). Returns true if it was stored (the user had none, or its key was revoked: the recovery key epoch continues, docs/recovery-key-lifecycle.md), false if exactly this key is active. Throws LastDeviceRecoveryException.InvalidKeyRegistration if the registration is for another user or its proof of possession does not verify, LastDeviceRecoveryKeyException.Conflict if the user has another active recovery key (only rotateLastDeviceRecoveryKey replaces it), and LastDeviceRecoveryKeyException.EpochExhausted if the recovery key epoch cannot grow any more.