Add SubscriberLimit and InvalidApi key pages classes

[MAILPOET-2200]

lib/AdminPages/Pages/SubscribersAPIKeyInvalid.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace MailPoet\AdminPages\Pages;
+
+use MailPoet\AdminPages\PageRenderer;
+use MailPoet\Models\Subscriber;
+
+if (!defined('ABSPATH')) exit;
+
+class SubscribersAPIKeyInvalid {
+  /** @var PageRenderer */
+  private $page_renderer;
+
+  function __construct(PageRenderer $page_renderer) {
+    $this->page_renderer = $page_renderer;
+  }
+
+  function render() {
+    $this->page_renderer->displayPage('invalidkey.html', [
+      'subscriber_count' => Subscriber::getTotalSubscribers(),
+    ]);
+  }
+}