Add top level fromList and toList functions in Cardano.Api.UTxO

[locallycompact]

Changelog

- description: |
    Define `fromList` and `toList` in `Cardano.Api.UTxO` module.
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  # - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
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  # - optimisation   # measurable performance improvements
  # - refactoring    # QoL changes
  # - bugfix         # fixes a defect
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  # - documentation  # change in code docs, haddocks...

Context

I'd like to add these because the user experience is annoying to have to import GHC.Exts when what I want to say is UTxO.fromList and UTxO.toList (a la Data.Map).

How to trust this PR

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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]

Why not just reexport GHC.fromList & GHC.toList from this module?

[locallycompact]

If it's imported from a qualified module, I think there's something beneficial to seeing the monomorphic type signature in the documentation. Otherwise it seems inconsistent. https://hackage.haskell.org/package/containers-0.4.0.0/docs/Data-Map.html#g:15