add chargebee.js file as library

Fixed #3360446 issue

src/Form/SettingsForm.php

@@ -90,11 +90,11 @@ class SettingsForm extends ConfigFormBase
 
 
 
-        $form['api']['integration_chargebee_api_js_link'] = array(
-          '#type' => 'textarea',
-          '#title' => t('JS Link'),
+        $form['api']['integration_chargebee_api_js_link'] = [
+          '#type' => 'checkbox',
+          '#title' => t('Use CDN version of Chargebee JS'),
           '#default_value' => $config->get('integration_chargebee_api_js_link'),
-        );
+        ];
 
 
         if (!empty($this->chargbee_plans)) {