[EuiDataGrid][A11y] Add contextual aria-label to column selector drag handle

[mgadewoll]

Summary

closes #8516

This PR updates EuiDataGrid and improve the accessibility of the column selector drag handle buttons by ensuring that the buttons have individually distinguishable accessible labels by adding the column title to it as context.

// before
drag handle button

// after
{column_name} drag handle button
e.g. Account drag handle button

Why are we making this change?

Accessibility: Improve the accessibility of the drag handles by ensuring unique labels.

Screenshots #

Screen.Recording.2025-12-19.at.11.17.02.mov

Impact to users

🟢 No updates required on consumer side.

ℹ️ Snapshots might require updates.

QA

• test EuiDataGrid's column selector with screen readers and verify that each drag handle button has a distinct accessible label

General checklist

• Browser QA
  • Checked in both light and dark modes
  • Checked in both MacOS and Windows high contrast modes
    • (emulate forced colors if you do not have access to a Windows machine.)
  • Checked in mobile
  • Checked in Chrome, Safari, Edge, and Firefox
  • Checked for accessibility including keyboard-only and screenreader modes
• Docs site QA
  • Added documentation
  • Props have proper autodocs (using @default if default values are missing) and playground toggles
  • Checked Code Sandbox works for any docs examples
• Code quality checklist
  • Added or updated jest and cypress tests
  • Updated visual regression tests
• Release checklist
  • A changelog entry exists and is marked appropriately
  • If applicable, added the breaking change issue label (and filled out the breaking change checklist)
  • If the changes unblock an issue in a different repo, smoke tested carefully (see Testing EUI features in Kibana ahead of time)
• Designer checklist
  • If applicable, file an issue to update EUI's Figma library with any corresponding UI changes. (This is an internal repo, if you are external to Elastic, ask a maintainer to submit this request)

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: d9f5845
• Documentation website
• Storybook

cc @mgadewoll

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: d9f5845

cc @mgadewoll