Adding New Builder

<?php
// Register header builder
Customify_Customizer_Layout_Builder()->register_builder( 'header', new Customify_Builder_Header() );

class Customify_Builder_Header  extends  Customify_Customizer_Builder_Panel{
    public $id = 'header';

    function get_config(){
        return array(
            'id'         => $this->id,
            'title'      => __( 'Header Builder', 'customify' ),
            'control_id' => 'header_builder_panel',
            'panel'      => 'header_settings',
            'section'    => 'header_builder_panel',
            'devices' => array(
                'desktop'   => __( 'Desktop', 'customify' ),
                'mobile'    => __( 'Mobile/Tablet', 'customify' ),
            ),
        );
    }

    function get_rows_config(){
        return array(
            'top' =>  __( 'Header Top', 'customify' ),
            'main' =>  __( 'Header Main', 'customify' ),
            'bottom' =>  __( 'Header Bottom', 'customify' ),
            'sidebar' =>  __( 'Mobile Sidebar', 'customify' ),
        );
    }

    function customize( ){

        $fn = 'customify_customize_render_header';
        $config = array(
            array(
                'name' => 'header_settings',
                'type' => 'panel',
                'theme_supports' => '',
                'title' => __( 'Header', 'customify' ),
            ),

            array(
                'name' => 'header_builder_panel',
                'type' => 'section',
                'panel' => 'header_settings',
                'title' => __( 'Header Builder', 'customify' ),
            ),

            array(
                'name' => 'header_builder_panel',
                'type' => 'js_raw',
                'section' => 'header_builder_panel',
                'theme_supports' => '',
                'title' => __( 'Header Builder', 'customify' ),
                'selector' => '#masthead',
                'render_callback' => $fn,
                'container_inclusive' => true
            ),
        );

        return $config;
    }

    function row_config(  $section = false, $section_name = false ){

        if ( ! $section ) {
            $section  = 'header_top';
        }
        if ( ! $section_name ) {
            $section_name = __( 'Header Top', 'customify' );
        }

        $selector = '#cb-row--'.str_replace('_', '-', $section );

        $fn = 'customify_customize_render_header';
        $selector_all = '#masthead';

        $config  = array(
            array(
                'name' => $section,
                'type' => 'section',
                'panel' => 'header_settings',
                'theme_supports' => '',
                'title' => $section_name,
            ),

            array(
                'name' => $section.'_layout',
                'type' => 'select',
                'section' => $section,
                'title' => __( 'Layout', 'customify' ),
                'selector' => $selector_all,
                'render_callback' => $fn,
                'choices' => array(
                    'default' =>  __( 'Default', 'customify' ),
                    'fullwidth' =>  __( 'Full Width', 'customify' ),
                    'boxed' =>  __( 'Boxed', 'customify' ),
                )
            ),

            array(
                'name' => $section.'_height',
                'type' => 'slider',
                'section' => $section,
                'theme_supports' => '',
                'device_settings' => false,
                'max' => 250,
                //'selector' => $selector.' .customify-grid, '.$selector,
                'selector' => $selector.' .customify-grid',
                'css_format' => 'min-height: {{value}};',
                'title' => __( 'Height', 'customify' ),
            ),
        );

        return $config;
    }
    function row_sidebar_config( $section , $section_name ){
        $selector = '#mobile-header-panel-inner';

        $config  = array(
            array(
                'name' => $section,
                'type' => 'section',
                'panel' => 'header_settings',
                'theme_supports' => '',
                'title'          => $section_name,
            ),

            array(
                'name' => $section.'_padding',
                'type' => 'css_ruler',
                'section' => $section,
                'selector' => $selector,
                'css_format' => array(
                    'top' => 'padding-top: {{value}};',
                    'right' => 'padding-right: {{value}};',
                    'bottom' => 'padding-bottom: {{value}};',
                    'left' => 'padding-left: {{value}};',
                ),
                'title' => __( 'Padding', 'customify' ),
            ),
            
        );
        return $config;
    }
}