getCurrentDeviceId

open override fun getCurrentDeviceId(): String

Get the device id registered for this application.

Notes

- If the application has not registered a device record, this method will
  throw an [`Other`](FxaError::Other) error.
    - (Yeah...sorry. This should be changed to do something better.)
- Device metadata is only visible to applications that have been
  granted the `https:///identity.mozilla.com/apps/oldsync` scope.