[boursorama] repaired new recipient

Some form names changed.

There is no more summaries for recipients when confirming. So I fetch
the new recipient from the list to confirm it and send it.

I precised some error messages.
I tested on the Timeout.

I got rid of build_recipient because we can directly transmit the
recipient.

In the load_state, I splitted between the handling of new recipient and
the strong authentication.