🎨 Palette: Add aria-labels to message queue icon-only buttons

[thirdeyenation]

💡 What: Added aria-label attributes to the icon-only buttons in the message queue component (Send all, Clear all, Send now, Remove).
🎯 Why: To improve screen reader support for icon-only action buttons.
📸 Before/After: Before, buttons had titles but no aria-labels. After, they have consistent aria-labels matching their functional actions.
♿ Accessibility: The accessible names now match the visual titles, enabling keyboard/screen reader users to understand the actions clearly.

---

PR created automatically by Jules for task 1712429245486143173 started by @thirdeyenation

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.