wip: add test suite and related_extensions array

[mathiusj]

WHY are these changes introduced?

Fixes #0000

WHAT is this pull request doing?

How to test your changes?

Post-release steps

Measuring impact

How do we know this change was effective? Please choose one:

• n/a - this doesn't need measurement, e.g. a linting rule or a bug-fix
• Existing analytics will cater for this addition
• PR includes analytics changes to measure impact

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes

[github-actions]

We detected some changes at packages/*/src and there are no updates in the .changeset.
If the changes are user-facing, run "pnpm changeset add" to track your changes and include them in the next release CHANGELOG.

[devisscher]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Add workflow for discount function settings #5096
• Nw hackdays37 extension workflow registry #5087
• wip: add test suite and related_extensions array #5092 👈 (View in Graphite)
• Start taking notes #5095
• main

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