Prior to this commit, Ledger.Constraints.Offchain.updateUtxoIndex would discard lookups for inputs that aren't script outputs. However, sometimes it is necessary to include particular public-key TxIns in a transaction, via Plutus.Contract.Wallet.ExportTx.lookups: a good example of this is when a Plutus.Contract.Currency.OneShotCurrency needs to consume a specified UTxO in its minting policy. Even though Plutus.Constraints.Tx.mustSpendPubKeyOutput adds a public-key input to the lookups, updateUtxoIndex discards that, with the result that it is only by chance that cardano-wallet would select that necessary input for the balanced transaction and provide it to Plutus validators. (Note that cardano-wallet does not automatically provide the TxIn in the partially constructed transaction to validators: it only provides Cardano.Wallet.PartialTx.inputs and the inputs it has semi-randomly chosen.) The consequence of all of this is that scripts that require a particular input will randomly fail during balancing in wallets with more than one UTxO.

This fix simply adds public-key inputs to the type Ledger.Constraints.OffChain.ScriptOutput so that it can also hold public-key inputs. (There might be a more descriptive name than ScriptOutput now.) It makes minor adjustments to the chain of functions that pass this into an unbalanced transaction before it is sent to cardano-wallet.

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