Test Conway CDDL using Cuddle

[nc6]

Description

This PR introduces cuddle, a Haskell library for declaring and validating CDDL documents.

This is then used to reflect the Conway CDDL specification (in eras/conway/impl/src/Cardano/Ledger/Conway/CDDL.hs) using a DSL known as Huddle.

libs/cardano-ledger-binary/testlib/Test/Cardano/Ledger/Binary/Cuddle.hs introduces utilities to run CDDL conformance tests using cuddle. These are currently based on a Huddle declaration, but it would be equally possible to use a native CDDL specification combined with cuddle's CBOR generators.

eras/conway/impl/test/Test/Cardano/Ledger/Conway/Binary/CddlSpec.hs then introduces a new set of tests based in the Huddle conway specification. The existing test suite is left untouched for now.

Checklist

• [x] Commit sequence broadly makes sense and commits have useful messages
• [x] New tests are added if needed and existing tests are updated
• [ ] When applicable, versions are updated in .cabal and CHANGELOG.md files according to the versioning process.
• [ ] The version bounds in .cabal files for all affected packages are updated. If you change the bounds in a cabal file, that package itself must have a version increase. (See RELEASING.md)
• [ ] All visible changes are prepended to the latest section of a CHANGELOG.md for the affected packages. New section is never added with the code changes. (See RELEASING.md)
• [x] Code is formatted with fourmolu (use scripts/fourmolize.sh)
• [x] Cabal files are formatted (use scripts/cabal-format.sh)
• [x] hie.yaml has been updated (use scripts/gen-hie.sh)
• [x] Self-reviewed the diff

[nc6]

Note that I have #4461 addressed, but planned to include that in a subsequent PR to avoid inflating this one.