Use list items for help option descriptions

[philderbeast]

Fixes #12422. Split from #12213.

I'll squash commits before applying the merge label if this pull request is approved.

Note

Please excuse the repetition for now. Once we've moved to use optparse-applicative with #12213, we could tackle only showing options relative to a command.

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• Patches conform to the coding conventions.
• Any changes that could be relevant to users have been recorded in the changelog.
  • Is the change significant? If so, remember to add significance: significant in the changelog file.
• The documentation has been updated, if necessary.
• Manual QA notes have been included.
• Tests have been added. (Ask for help if you don’t know how to write them! Ask for an exemption if tests are too complex for too little coverage!)