feat(accordion): add css custom properties

[yuhsianw]

PR Checklist

Please check if your PR fulfills the following requirements:

• [ ] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been added / updated (for bug fixes / features)
• [ ] If applicable, have a visual design approval

PR Type

What kind of change does this PR introduce?

• [ ] Bugfix
• [x] Feature
• [ ] Code style update (formatting, local variables)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [ ] Documentation content changes
• [ ] clarity.design website / infrastructure changes
• [ ] Other... Please describe:

What is the current behavior?

Issue Number: https://github.com/vmware-clarity/core/issues/278

What is the new behavior?

--box-shadow, --icon-visibility, and --icon-margin CSS custom properties added to cds-accordion-header.

Does this PR introduce a breaking change?

• [ ] Yes
• [x] No

Other information

[github-actions[bot]]

👋 @yuhsianw,

• 🙏 The Clarity team thanks you for opening a pull request
• 🎉 The build for this PR has succeeded
• 🔍 The PR is now ready for review
• 🍿 In the meantime, checkout out a preview of this PR
• 🖐 You can always follow up here. If you're a VMware employee, you can also reach us on our internal #clarity-support Slack channel

Thank you,

🤖 Clarity Release Bot

[github-actions[bot]]

:tada: This PR is included in version 6.9.0 :tada:

The release is available on:

• GitHub release
• v6.9.0

Your semantic-release bot :package::rocket:

[github-actions[bot]]

Hi there 👋, this is an automated message. To help Clarity keep track of discussions, we automatically lock closed PRs after 14 days. Please look for another open issue or open a new issue with updated details and reference this one as necessary.