- adds audible messages via `wp.a11y.speak()` to announce the search results
- removes a `keyup` event that was there only to support old browsers
- removes `aria-modal="true"` from the media modal dialog as it prevents the ARIA live regions to be perceived by screen readers
- triggers the search only after 2 ASCII characters have been typed
Props anevins, antpb, aduth, loreleiaurora, afercia.
Fixes#47146.
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