Add pending icon next to balance while transaction is confirming

[listenaddress]

Balance took ~5 seconds to update, after the transaction was confirmed. It's a nice to have, but it'd help user confidence in the app if that balance reflected the change right away.

[Schwartz10]

I think this would take a fair amount of technical complexity with the current setup for (imo) not a huge gain. I think we should provide some other feedback mechanism in the UI (like a loading indicator) to show that the balance is listening for an update.