core: Babysit refund transactions.

[JoeGruffins]

Core should treat refunds the same as redeems, not letting the trade complete until a refund has some number of confirmations and possibly sending new transactions if necessary, especially in the case of account based assets.

[buck54321]

Oof. Quite the oversight. Let's prioritize this.

[JoeGruffins]

I can work on this.

[buck54321]

Thanks, @JoeGruffins. To note, we monitor transactions for finality for EVM assets internally already, but not UTXO assets. This issue is about how core handles finality though. We should probably look closely at how we handle responsibility sharing in this area.