Core: Fix boolean true args in URL getting ignored

[JReinhold]

Closes #25035
Closes #23623 (although it probably doesn't fix #23623 (comment) which sounds like a separate issue)

What I did

Changed the args mapping to expect actual booleans as input instead of 'true' and 'false'. Now it recognises both 'true' and true as true and anything else as false. meaning that both myArg:!true (what Storybook does) and myArg:true (a user could manually do this) in the URL will be parsed as true.

Thanks to @dcherman for the suggestion which pinpointed the exact issue.

This bug was likely introduced in #21102 that explicitly converts string boolean types to boolean types before sending them throughout the system, and then the mapper just wasn't updated with it.

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

1. Open the secondary button story in any sandbox.
2. Set primary to true in controls
3. Reload and still see the button being primary and the arg in the URL still being there

Before this fix, the button would revert back to being secondary because the arg would be removed from the URL

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 PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

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

[valentinpalkovic]

LGTM!

[shilman]

@JReinhold @valentinpalkovic marking this as patch. lmk if you disagree!