Completion from dune

[ElectreAAS]

With ocaml/dune#14779, we now generate completion scripts for dune.
Could we ship those instead of the ones generated by climate?
No slight against climate of course, but since Steve is no longer in the team, maintenance is going to be an issue

[Leonidas-from-XIV]

Yes, I think once that support is merged I think it would be cool to change the code to generate the cmdliner completions instead of the current bash completion. That will at least give us completion for ZSH and also more likely to stay up-to-date.