Make the bytestring generator generate variations #95
Description
In the ledger codebase we currently have a Twiddle typeclass that is used to introduce variations into encoded bytes. The idea is that CDDL doesn't specify exactly how to encode certain type, for example lists can be encoded as a definite or an indefinite list. The bytestring generator should generate all of these variations to test that the decoders don't make any wrong assumptions about how these types need to be encoded.