ISTWCMS-4656 Add link plugin and fakeobject plugin which is used by the link plugin.

src/Plugin/CKEditorPlugin/FakeObjectPlugin.php

+<?php
+
+namespace Drupal\uw_cfg_common\Plugin\CKEditorPlugin;
+
+use Drupal\ckeditor\CKEditorPluginBase;
+use Drupal\Core\Asset\LibrariesDirectoryFileFinder;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\editor\Entity\Editor;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Defines the "fakeobjects" plugin.
+ *
+ * @CKEditorPlugin(
+ *   id = "fakeobjects",
+ *   label = @Translation("FakeObjects")
+ * )
+ */
+class FakeObjectPlugin extends CKEditorPluginBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * Library file finder.
+   *
+   * @var \Drupal\Core\Asset\LibrariesDirectoryFileFinder
+   */
+  protected $libFileFinder;
+
+  /**
+   * Constructs a BlockComponentRenderArray object.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin ID for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\Core\Asset\LibrariesDirectoryFileFinder $libFileFinder
+   *   The library file finder.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, LibrariesDirectoryFileFinder $libFileFinder) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->libFileFinder = $libFileFinder;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static($configuration, $plugin_id, $plugin_definition, $container->get('library.libraries_directory_file_finder'));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getConfig(Editor $editor) {
+    return [];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getButtons() {
+    return [];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFile() {
+    return $this->libFileFinder->find('ckeditor.fakeobjects') . '/plugin.js';
+  }
+
+}

src/Plugin/CKEditorPlugin/LinkPlugin.php

+<?php
+
+namespace Drupal\uw_cfg_common\Plugin\CKEditorPlugin;
+
+use Drupal\ckeditor\CKEditorPluginBase;
+use Drupal\Core\Asset\LibrariesDirectoryFileFinder;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\editor\Entity\Editor;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Defines the "link" plugin.
+ *
+ * @CKEditorPlugin(
+ *   id = "link",
+ *   label = @Translation("link")
+ * )
+ */
+class LinkPlugin extends CKEditorPluginBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * Library file finder.
+   *
+   * @var \Drupal\Core\Asset\LibrariesDirectoryFileFinder
+   */
+  protected $libFileFinder;
+
+  /**
+   * Constructs a BlockComponentRenderArray object.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin ID for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\Core\Asset\LibrariesDirectoryFileFinder $libFileFinder
+   *   The library file finder.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, LibrariesDirectoryFileFinder $libFileFinder) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->libFileFinder = $libFileFinder;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static($configuration, $plugin_id, $plugin_definition, $container->get('library.libraries_directory_file_finder'));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDependencies(Editor $editor) {
+    return [
+      'fakeobjects',
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getLibraries(Editor $editor) {
+    return [];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getConfig(Editor $editor) {
+    return [];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getButtons() {
+    $libraryUrl = $this->libFileFinder->find('ckeditor.link');
+    return [
+      'Link' => [
+        'label' => $this->t('Link'),
+        'image' => $libraryUrl . '/icons/link.png',
+      ],
+      'Unlink' => [
+        'label' => $this->t('Unlink'),
+        'image' => $libraryUrl . '/icons/unlink.png',
+      ],
+      'Anchor' => [
+        'label' => $this->t('Anchor'),
+        'image' => $libraryUrl . '/icons/anchor.png',
+      ],
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFile() {
+    return $this->libFileFinder->find('ckeditor.link') . '/plugin.js';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function isInternal() {
+    return FALSE;
+  }
+
+}