Updates on send coin

[tomt1664]

For the client:

After sending a coin, that coin should be removed from the balance. But the client should still be listed, and the client can re-send the coin to a different address if required. These coin are in 'send in progress' status.

Add a new function that updates the status of 'send in progress' coins. If coins have completed 'transfer_receiver' then remove them from the client.

This can be determined by calling /info/statechain/ {statechain_id} for each coin. If the enclave_pubkey has changed to match a different key share, the coin has been received.