Implement the postgres 'reverse' func

[DAlperin]

closes https://github.com/MaterializeInc/database-issues/issues/7093

Motivation

Tips for reviewer

Checklist

• This PR has adequate test coverage / QA involvement has been duly considered. (trigger-ci for additional test/nightly runs)
• This PR has an associated up-to-date design doc, is a design doc (template), or is sufficiently small to not require a design.
• If this PR evolves an existing $T ⇔ Proto$T mapping (possibly in a backwards-incompatible way), then it is tagged with a T-proto label.
• If this PR will require changes to cloud orchestration or tests, there is a companion cloud PR to account for those changes that is tagged with the release-blocker label (example).
• If this PR includes major user-facing behavior changes, I have pinged the relevant PM to schedule a changelog post.

[github-actions]

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[DAlperin]

I have read the Contributor License Agreement (CLA) and I hereby sign the CLA.

[DAlperin]

recheck

[ParkMyCar]

LGTM! Although we might need to regen the docs (details), let's see what CI says!