`Datums` and `Redeemers` should be removed from the `SCLogic` trait`

[MitchTurner]

Currently SCLogic includes the associated types:

    type Endpoints: Send + Sync;
    type Lookups: Send + Sync;
    type LookupResponses: Send + Sync;
    type Datums: Clone + Eq + Debug + Send + Sync;
    type Redeemers: Clone + PartialEq + Eq + Hash + Send + Sync;

This was meant to constrain the LedgerClient to be able to handle the correct Datums and Redeemers. This might not be necessary anymore, now that we have a domain concept of PlutusData and conversions between.

It might be better to put the conversion constraint at the implementation level if you want the conversion guarantees.