Function deltachat::imex::transfer::on_blob

async fn on_blob(
    context: &Context,
    progress: &ProgressEmitter,
    jobs: &Mutex<JoinSet<()>>,
    ticket: &Ticket,
    _hash: Hash,
    reader: DataStream,
    name: String
) -> Result<DataStream>

Get callback when a blob is received from the provider.

This writes the blobs to the blobdir. If the blob is the database it will import it to the database of the current Context.