Integration: wire into cardano-ledger

[qnikst]

Adopt the new envelope in cardano-ledger: consume format-scls APIs, ensure all writers produce the new format, and all readers handle it (plus optional legacy mode while migrating).

Deliverables / Acceptance:

• Implement new type class for UtxoIn key
• Use new API to load utxo.hex file in the scls format

[qnikst]

There was a first step of the integration.
I've managed to update the repo and the code.

There are minor problems that I'm not sure about. Previously we had two types of the key in utxo namespace for the certificates and for the utxoin. However certificates keys are not used on the existing codepath, that makes me worried about if we are storing the values properly. Currently I'm investigating that.

The plan to test by including the code into the performance benchmarks didn't work as we have to update the code to support the values that are emitted by the cardano-cli and following review with the current code in master does not lead to results. If we want to continue with that approach we will have to update the code first.