DataForm select control: support validation

[oandregal]

Part of #71500

What?

Add support for required and custom validation in the select control.

Why?

So that all controls support basic validation.

How?

Use the existing ValidatedSelectControl component.

Testing Instructions

In the storybook (npm run storybook:dev) verify that it can take required and custom validation in the "DataViews > DataForm > Validation" story:

Screen.Recording.2025-09-15.at.16.12.51.mov

[github-actions]

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Co-authored-by: oandregal <[email protected]>
Co-authored-by: andrewserong <[email protected]>

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[github-actions]

Flaky tests detected in 6b0c1bd.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/17736188398
📝 Reported issues:

• [Flaky Test] Redirection after template creation #60678 in /test/e2e/specs/site-editor/site-editor-url-navigation.spec.js
• [Flaky Test] should refresh the page when stylesheet loading fails #71135 in /test/e2e/specs/interactivity/router-styles.spec.ts

[andrewserong]

Tests well for me!

✅ Custom validation state works as expected (must select Option 1)
✅ Required validation state works as expected
✅ Toggling both off works as expected

LGTM!