Loads classic theme styles on classic themes in the frontend.

This is needed for backwards compatibility for button blocks specifically.

function wp_enqueue_classic_theme_styles() {
	if ( ! WP_Theme_JSON_Resolver::theme_has_support() ) {
		$suffix = wp_scripts_get_suffix();
		wp_register_style( 'classic-theme-styles', '/' . WPINC . "/css/classic-themes$suffix.css", array(), true );
		wp_enqueue_style( 'classic-theme-styles' );
	}
}