🎨 Palette: Add tooltips to 'More options' buttons

[dlukt]

🎨 Palette: Add tooltips to 'More options' buttons

Adds android:tooltipText to 'More options' icon-only buttons (options_btn)
in list item layouts (item_generic_list_options.xml, item_account_list.xml,
and item_account_list_onboarding.xml). This improves accessibility and UX
by ensuring a descriptive hover and long-press tooltip is displayed for users
on API 26+ devices, bringing parity with screen reader descriptions.

---

PR created automatically by Jules for task 14671264492684175417 started by @dlukt

[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.