[DOM] Preserve autofocus for controls inside dialogs

[bestmaa]

Summary

Fixes#23301.

React implements autoFocus on client-created controls by calling focus() during commit and omitting the native autofocus attribute. That call has no effect while a parent dialog is closed, so opening the dialog later lets the browser focus the first focusable control instead.

This change:

• preserves the native autofocus attribute for button, input, select, and textarea elements inside a dialog;
• keeps the attribute synchronized when the autoFocus prop changes;
• leaves existing behavior outside dialogs and during hydration unchanged.

The logic lives in the DOM host config so dialog-specific behavior stays out of the reconciler.

How did you test this change?

• yarn test ReactDOM-test ReactDOMComponent-test ReactServerRenderingHydration-test --runInBand — 208 tests passed in experimental development mode
• yarn test-stable ReactDOM-test ReactDOMComponent-test ReactServerRenderingHydration-test --runInBand — 208 tests passed
• yarn test ReactDOM-test ReactDOMComponent-test ReactServerRenderingHydration-test --prod --runInBand — 208 tests passed
• yarn linc
• yarn flow dom-browser
• yarn prettier
• Docker clean-room runs with Node 20.19.0 and Yarn 1.22.22
• React DOM bundle verified with Playwright in Chromium, Firefox, and WebKit: after dialog.showModal(), the control with autoFocus became document.activeElement

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[dianatofficial]

Approved. The fix is minimal and correct.