Add golden test for cardano-testnet help

[newhoggy]

Description

We care about the help usage of the cardano-testnet as well, for example: #5234, so it's good to have golden tests for them.

Depends on #5206

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. These may include:
  • golden tests
  • property tests
  • roundtrip tests
  • integration tests
    See Runnings tests for more details
• Any changes are noted in the CHANGELOG.md for affected package
• The version bounds in .cabal files are updated
• CI passes. See note on CI. The following CI checks are required:
  • Code is linted with hlint. See .github/workflows/check-hlint.yml to get the hlint version
  • Code is formatted with stylish-haskell. See .github/workflows/stylish-haskell.yml to get the stylish-haskell version
  • Code builds on Linux, MacOS and Windows for ghc-8.10.7 and ghc-9.2.7
• Self-reviewed the diff

Note on CI

If your PR is from a fork, the necessary CI jobs won't trigger automatically for security reasons.
You will need to get someone with write privileges. Please contact IOG node developers to do this
for you.

[carbolymer]

I think we should bump cabal-version when we're using newer cabal features.

[newhoggy]

This feature was introduced in cabal 3.0 and many other projects that this feature are still on cabal-version: 3.0.

[carbolymer]

https://cabal.readthedocs.io/en/stable/cabal-package.html#library

For packages using cabal-version: 3.4 or higher, the syntax to specify an internal library in a build-depends: section is package-name:internal-library-name.

[Jimbo4350]

Nice work 👍

[Jimbo4350]

Accidentally generated?

[newhoggy]

Code has been modified to not generate this file.