MDL-26675 block_rss_client: Add a new feed in the RSS block form

The patch added a couple of things:
- Add a new feed in the RSS block form
- Make the image responsive to the parent container
- Each feed now includes a channel link

blocks/rss_client/classes/output/feed.php

@@ -44,6 +44,13 @@ class feed implements \renderable, \templatable {
      */
     protected $title = null;
 
+    /**
+     * The feed's channel link.
+     *
+     * @var string|null
+     */
+    protected ?string $channellink;
+
     /**
      * An array of renderable feed items
      *
@@ -78,11 +85,13 @@ class feed implements \renderable, \templatable {
      * @param string $title The title of the RSS feed
      * @param boolean $showtitle Whether to show the title
      * @param boolean $showimage Whether to show the channel image
+     * @param string|null $channellink The channel link of the RSS feed
      */
-    public function __construct($title, $showtitle = true, $showimage = true) {
+    public function __construct($title, $showtitle = true, $showimage = true, ?string $channellink = null) {
         $this->title = $title;
         $this->showtitle = $showtitle;
         $this->showimage = $showimage;
+        $this->channellink = $channellink;
     }
 
     /**
@@ -97,6 +106,7 @@ class feed implements \renderable, \templatable {
             'title' => $this->showtitle ? $this->title : null,
             'image' => null,
             'items' => array(),
+            'channellink' => $this->channellink ?? null,
         );
 
         if ($this->showimage && $this->image) {
@@ -131,6 +141,15 @@ class feed implements \renderable, \templatable {
         return $this->title;
     }
 
+    /**
+     * Set the feed channel link.
+     *
+     * @param \moodle_url|null $channellink the URL to the channel website.
+     */
+    public function set_channellink(?\moodle_url $channellink) {
+        $this->channellink = $channellink;
+    }
+
     /**
      * Add an RSS item
      *