Allow an output file to be specified for query pool-state

[neilmayhew]

Changelog

- description: |
    Allow an output file to be specified for the various versions of query pool-state
# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
  - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  - improvement    # QoL changes e.g. refactoring
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

No corresponding issue.

How to trust this PR

• Most of the changed lines are in golden files.
• Output logic was copied from other commands.

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

[smelc]

Approving to avoid blocking, but please apply my suggestion 👍

Thanks for your neat contribution!

[smelc]

@neilmayhew> @-tag me when you want to merge, in case you don't have the right to do so. I'll merge on your behalf.

[neilmayhew]

@neilmayhew> @-tag me when you want to merge, in case you don't have the right to do so. I'll merge on your behalf.

@smelc Thanks. I don't have the right.

[neilmayhew]

Suggestion added, and rebased on main