[__SELECT__v][BUTTON]
[__SELECT__v][BUTTON]

$form['select_g1'] = array(
                    '#type' => 'select',
                    '#prefix' => '<div class="container-inline">',
                    '#title' => t('Select &emsp; &emsp; &emsp;&emsp;'),
                    '#options' => $contarray,
                    '#empty_value' => '',
                    '#default_value' => ($ext) ? $row['model'] : "",
                    );
$form['button'] = array(
                    '#markup' => ' <a target="_blank" href=""><span class="button js-form-submit form-submit"><img src="/sites/default/buttons/edit.png"></span></a></div>',
                    );

mymodule.updatelink:
  version: VERSION
  js:
    js/updatelink.js: {}
  dependencies:
    - core/jquery
    - core/drupal

$form['#attached']['library'][] = 'mymodule/mymodule.updatelink';