Add compatible command group

[Jimbo4350]

Related: #926

Changelog

- description: |
    Introduce "compatible" command group
  type:
  - feature        # introduces a new feature
  - compatible     # the API has changed but is non-breaking

Context

Usage: cardano-cli compatible 
                                ( shelley
                                | allegra
                                | mary
                                | alonzo
                                | babbage
                                | conway
                                )

  Limited backward compatible commands for testing only.

Available options:
  -h,--help                Show this help text

Available commands:
  shelley                  Shelley era commands
  allegra                  Allegra era commands
  mary                     Mary era commands
  alonzo                   Alonzo era commands
  babbage                  Babbage era commands
  conway                   Conway era commands

How to trust this PR

Highlight important bits of the PR that will make the review faster. If there are commands the reviewer can run to observe the new behavior, describe them.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[carbolymer]

Parsers should go to cardano-cli/src/Cardano/CLI/Compatible/Options/Common.hs or something similar

[Jimbo4350]

I don't want to mirror the previous EraBased directory structure. A Common module is fine but this parser is not common i.e it's called in one place.

[carbolymer]

This file should be named
cardano-cli/src/Cardano/CLI/Compatible/Options/Governance.hs

[Jimbo4350]

Same as above, I don't want to mirror the previous directory structure.

[carbolymer]

This module should be split into Run, Option and Command modules

[Jimbo4350]

#917 (comment)

[carbolymer]

What's the plan with Eons and compatible commands? Are we planning to keep necessary eons for those commands?

[Jimbo4350]

What's the plan with Eons and compatible commands? Are we planning to keep necessary eons for those commands?

Currently those eons will be intended for use only with our compatibility commands and we should add this to the haddocks in cardano-api. This will limit the scope of how much intra era compatibility code we have to write vs before where we had to write and maintain code for everything that changed between eras.