Implement merge functionality for variation connected fields

[razwan]

                    case 'light_dark_color':
                        swapConnectedFields( {
                            'sm_color_primary': 'sm_light_primary',
                            'sm_color_secondary': 'sm_light_secondary',
                            'sm_color_tertiary': 'sm_light_tertiary',
                            'sm_dark_primary': [],
                            'sm_dark_secondary': [],
                            'sm_dark_tertiary': [],
                            'sm_light_primary': ['sm_color_primary', 'sm_dark_primary'],
                            'sm_light_secondary': ['sm_color_secondary', 'sm_dark_secondary'],
                            'sm_light_tertiary': ['sm_color_tertiary', 'sm_dark_tertiary'],
                        } );
                        break;