Remove simple script distinction

[Jimbo4350]

Resolves: #4261

• Timelock scripts are a superset of MultiSig scripts in that they can also express validation in terms of before or after a particular slot.

• In cardano-ledger the serialization of Timelock and MultiSig scripts are identical.

Due to these properties, it is not necessary to distinguish between MultiSig and Timelock scripts. We can default to Timelock scripts without issue.

[newhoggy]

I'm wondering if it might be better not to error here.

Using error from the CLI is okay, but error would cause an application that uses the API to exit.

[Jimbo4350]

So I opted to return an Either as you suggested for toShelleyMultiSig because this is a function a consumer of the api is likely to use and potentially shoot themselves in the foot. However toShelleyMultiSig is called in: toShelleyScript :: ScriptInEra era -> Ledger.Script (ShelleyLedgerEra era). I opted to error here instead because this will error if someone is running a Shelley era network and tries to use a Timelock. I think the odds of this is extremely low and not worth polluting the code further with an Either. Lmk what you think.

[newhoggy]

I think let this pass for now given the low probably of it being a problem, but we should also create a ticket to remove calls to error from cardano-api as a separate piece of work to be done after the next release.