What?

Closes #71491

Adds a JavaScript filter blockEditor.linkControl.searchItemIcon to the <SearchItemIcon /> component to allow customizing the icon displayed in Link Control search suggestions.

Why?

Currently, custom post types cannot display their registered icons within the Link Control search results. This PR solves this by exposing a filter, allowing developers to inject custom SVG icons for specific custom post types or suggestion types (custom tax).

How?

Wraps the resolved icon variable in the SearchItemIcon component with applyFilters. This passes the default icon and the suggestion.type (post type) to the filter before rendering the final @wordpress/icons component.

Testing Instructions

1. Enqueue a custom script in the editor, or open your browser console in the Block Editor.
2. Add a filter to replace an icon for a specific post type (e.g., overriding pages or targeting a CPT):

import { verse } from '@wordpress/icons';
import { addFilter } from '@wordpress/hooks';

addFilter(
	'blockEditor.linkControl.searchItemIcon',
	'test-plugin',
	( icon, suggestionType ) => {
		if ( suggestionType === 'rt-movie' ) {
			return verse;
		}
		return icon;
	}
);

3. Insert a Paragraph block and type some text.
4. Highlight the text and press Cmd/Ctrl + K to open the Link Control.
5. Search for the targeted post type.
6. Verify that your custom icon appears next to the search result.

Screenshots or screencast

Before	After