ConwayRedeemer should preserve ordering when decoding from CBOR

[agaffney]

We store the redeemers in a map, but we need to preserve the order for re-encoding to CBOR

[agaffney]

All we really need to do is make sure that we use the AlonzoRedeemer type to store the data when the on-chain data is in the legacy list format. We can rely on the CBOR encoder for key ordering in the ConwayRedeemer map format.