Support terms for number range and slider indexing

<?php
/** fixes values based on term slugs to be numberic by looking up term name **/
add_filter( 'facetwp_index_row', function( $params, $class ) {
    $term_id = (int) $params['term_id'];
    $value = $params['facet_value'];

    if ( 0 < $term_id && in_array( $class->facet['type'], [ 'number_range', 'slider' ] ) && !is_numeric( $value ) ) {
        // lookup term name
        $term = get_term( $term_id );
        if ( !empty( $term ) ) {
            $params['facet_value'] = $term->name;
        }
    }

    return $params;
}, 11, 2 );