Create subscribers response builder

[MAILPOET-2653]

lib/API/JSON/ResponseBuilders/SubscribersResponseBuilder.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace MailPoet\API\JSON\ResponseBuilders;
+
+use MailPoet\Entities\SubscriberEntity;
+
+class SubscribersResponseBuilder {
+
+  public function build(SubscriberEntity $subscriberEntity): array {
+    $data = [
+      'id' => $subscriberEntity->getId(),
+      'wp_user_id' => $subscriberEntity->getWpUserId(),
+      'is_woocommerce_user' => $subscriberEntity->getIsWoocommerceUser(),
+      'subscriptions' => [],// TODO
+      'unsubscribes' => [],// TODO
+      // TODO custom fields
+      'status' => $subscriberEntity->getStatus(),
+      'last_name' => $subscriberEntity->getLastName(),
+      'first_name' => $subscriberEntity->getFirstName(),
+      'email' => $subscriberEntity->getEmail(),
+    ];
+
+    return $data;
+  }
+}