…#453)

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## Description

I needed this, so I made it. It's nothing too complex: we just
pretty-print the `schemars` schema for the root `Metadata` type.

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## Changelog

- Add a changelog entry (in the "Changelog entry" section below) if the
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### Product
_(Select all products this will be available in)_
- [ ] community-edition
- [ ] cloud
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### Type
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- [ ] highlight
- [ ] enhancement
- [ ] bugfix
- [ ] behaviour-change
- [ ] performance-enhancement
- [ ] security-fix
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### Changelog entry
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V3_GIT_ORIGIN_REV_ID: a9e75bfa06c35577c17d8cbf0d021b1f56826a28