fix(ActionBar): fix icon color in close button in emphasized ActionBar

[reidbarber]

Fixes a contrast failure in the S2 ActionBar's clear button. In dark mode with isEmphasized, the close button's icon was hardcoded to white, which failed contrast against the ActionBar background color.

Changed to transparent-overlay-1000, which auto-computes black or white based on the --s2-container-bg inherited from the container.

Also added a chromatic story.

Before:

After:

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices

📝 Test Instructions:

Verify in docs/storybook and check new Chromatic story.

🧢 Your Project:

[snowystinger]

thanks, not sure how i missed that when i updated the other button