Cardano Updates

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

Remove `NoThunks` instances for predicate failures and `ContextError` types

`NoThunks` instances are used for memory leak detection during development,
but predicate failures should never be retained in the ledger state - they
are only used for validation results. Removing these instances reduces
code maintenance burden and instance derivation overhead.

This change removes `NoThunks` instances from:

- All predicate failure types across Shelley, Allegra, Alonzo, Babbage,
  Conway, and Dijkstra eras
- All predicate failures in cardano-protocol-tpraos
- All `ContextError` types (`AlonzoContextError`, `BabbageContextError`,
  `ConwayContextError`, `DijkstraContextError`)
- The `NoThunks (ContextError era)` constraint from the `EraPlutusContext` class
- The `NoThunks` deriving instance for `CollectError`

Add nixfmt in our Github CI checks

`NoThunks` instances are used for memory leak detection during development,
but predicate failures should never be retained in the ledger state - they
are only used for validation results. Removing these instances reduces
code maintenance burden and instance derivation overhead.

This change removes `NoThunks` instances from:

- All predicate failure types across Shelley, Allegra, Alonzo, Babbage,
  Conway, and Dijkstra eras
- All predicate failures in cardano-protocol-tpraos
- All `ContextError` types (`AlonzoContextError`, `BabbageContextError`,
  `ConwayContextError`, `DijkstraContextError`)
- The `NoThunks (ContextError era)` constraint from the `EraPlutusContext` class
- The `NoThunks` deriving instance for `CollectError`

* Add ./script/nix-format.sh for non-Nix users.
* Add nixfmt in our Nix pre-commit hook.
* Add Github CI check