Transaction builder / signer DSL & Byron implementation

[KtorZ]

ChangeLog

• 7b4507142f739dd59761f7dc982ac58cd4f3ef3f :round_pushpin: write simple DSL for transaction construction

• 3b8480d002432cd85f1c99ebb266608b4219f7d6 :round_pushpin: first draft implementation of Cardano Byron transactions

Comments

Still very drafty and lack of unit tests. But I've started grooming a bit the structure and it looks pretty nice so far.

[paweljakubas]

@KtorZ The abstraction works very ok for Byron, but are we sure it is going to accommodate what is coming for Shelley : https://github.com/input-output-hk/cardano-ledger-specs/blob/f1d5ddb25531b2512796d34e9cfd803f7af76567/shelley/chain-and-ledger/executable-spec/src/Shelley/Spec/Ledger/Tx.hs#L56