Do not try to look up a UTxO datum in processConstraints when spending

[klntsky]

cardano-transaction-lib/src/Internal/ProcessConstraints.purs

Line 555 in 2c8e8fb

liftAff $ queryHandle.getDatumByHash dHash <#> hush

We don't really need to try to do this automatically, because that way we introduce implicit, non-obvious for the user dependency on the blockchain state. If the datum isn't provided for a datum hash in an output, we should just fail.