Feature: Icons and CSS class names are configurable 

Description 

The editing surface no longer decides on its own which glyph an action draws or which CSS classes its elements carry. Both are configured by the installation:

$GLOBALS['TYPO3_CONF_VARS']['modern_extbase_frontend_edit'] = [
    'icons' => [
        'edit' => 'actions-open',
    ],
    'classes' => [
        'button' => 'button',
        'buttonPrimary' => 'button--primary',
        'control' => 'form-control',
    ],
];

The class names are added to the ones the surface always carries, which is what lets it pick up a site's own button and form styling rather than imitating it. The icons are resolved through TYPO3's icon registry on the server, so an icon can also be replaced by re-registering its identifier from another extension. Neither needs a JavaScript build.

Impact 

Nothing has to be configured. Without any configuration the surface draws the icons the extension ships and carries only its own class names, exactly as before.