PLT-6750: Parsing pretty printed Marlowe contracts

[yveshauser]

This PR addresses #645

Run marlowe-cli format --help to display the help of the newly introduced command.

The goal is to provide a command line tool to allow conversion between pretty-printed Marlowe contracts and the JSON representation of a Marlowe contract (default). Note, that with another ticket we will introduce also an official grammar for pretty printed Marlowe in https://github.com/input-output-hk/marlowe, that will also allow blockchain agnositc parsing of Marlowe contracts.

Pre-submit checklist:

• Branch
  • Tests are provided (if possible)
  • Test report is updated (if relevant)
  • Commit sequence broadly makes sense
  • Key commits have useful messages
  • Relevant tickets are mentioned in commit messages
  • Formatting, PNG optimization, etc. are updated
• PR
  • Self-reviewed the diff
  • Useful pull request description
    • Review required
    • Substantial changes to code, test, or documentation
    • Change made to Marlowe validator (@bwbush and @palas must be included as reviewers)
    • Review not required
    • Minor changes to non-critical code, documentation, nix derivations, configuration files, or scripts
    • Formatting, spelling, grammar, or reorganization
  • Reviewer requested

[palas]

Nicely done! I am quite convinced the code is correct, and the test you wrote should give good coverage. I have written a couple of suggestions for improved usability and a couple of other minor things

[bwbush]

Looks good, aside from the one concern I noted in a comment. Thanks!

[palas]

Nice 👍