Cardano Updates

Use `bspWitnessScripts` and `bspReferenceScripts` fields from
`BabbageScriptsProvided` instead of recomputing them.

Refactor such that each example from an era is build on top of the
example of the previous era.

Allows:
* reduced duplication
* each example of each era has most fields set with values

Since `ContextError`s are never stored and their reporting doesn't need
to be efficient (we always optimize for the positive case with valid
transactions, as invalid transactions don't propagate through the
network), there's no need for strictness annotations on the error
constructors.

This change removes the bang patterns (!) from:
- AlonzoContextError
- BabbageContextError
- ConwayContextError
- DijkstraContextError

`validateOutsideForecast`, `validateOutputTooBigUTxO`

ScriptPurpose aware memoization of TxInfo