Export the Committee record from the ledger, for use in the CLI

[smelc]

Changelog

- description: |
    Export the Committee record from the ledger, for use in the CLI
# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
  - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  # - refactoring    # QoL changes
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

• Required for create-testnet-data: support creating committee (using conway genesis) cardano-cli#757
• That's this record: https://github.com/IntersectMBO/cardano-ledger//blob/4be8d27282383d6872ff7ee3bd1b4ee11985f4f3/eras/conway/impl/src/Cardano/Ledger/Conway/Governance/Procedures.hs#L532
• This type is used for declaring committee members in Conway's genesis file

How to trust this PR

It's only a small export

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• Self-reviewed the diff