Allows querying offers made in the past, which were either cancelled or accepted. Unspent offers are ignored.
This reflects what users would expect an "exchange" UX pretty closely: "activeOffers*" is the orderbook, "historicOffers" are the candlesticks (and also the cancelled offers, but those would have to be ignored).
They can also be queried by pubkey, giving users a history of their offers.
This is done by going through the tx history of the token ID/group token ID/pubkey group of the agora plugin, and looking at *inputs* that spend an agora output. We then reconstruct the Utxo, and then we just re-use the _parseOfferUtxo function, which we also gave a status.