UI: Fix sidebar top and bottom addons not showing

[ndelangen]

Closes #25809

What I did

The memoization was broken, because the result of getElements is a constant that gets mutated upstream, so the useMemo never gets re-executed.

By making the concatinated keys of the object (a single string) the memo key, it will get re-evaluated and thus we'll get a consistent array, but a new one, as soon as an new addon gets injected.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

This pull request has been released as version 0.0.0-pr-25825-sha-bbd3f181. Try it out in a new sandbox by running npx [email protected] sandbox or in an existing project with npx [email protected] upgrade.

More information

Published version	0.0.0-pr-25825-sha-bbd3f181
Triggered by	@ndelangen
Repository	storybookjs/storybook
Branch	norbert/fix-memo-in-ui
Commit	bbd3f181
Datetime	Tue Jan 30 20:22:01 UTC 2024 (1706646121)
Workflow run	7717006552

To request a new release of this pull request, mention the @storybookjs/core team.

core team members can create a new canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=25825

[ndelangen]

I triggered the canary deploy