MDL-82160 renderer: Add render_context_header method to core_renderer

In MDL-81597 the original render_context_header method was removed and converted to a template.
That caused a regression, so this patch adds the method again but using the new template.

.upgradenotes/MDL-82160-2024061112162023.yml

@@ -0,0 +1,7 @@
+issueNumber: MDL-82160
+notes:
+  theme:
+    - message: >-
+        The method `core_renderer::render_context_header` has been deprecated
+        please use core_renderer::render($contextheader) instead
+      type: deprecated

lib/outputrenderers.php

@@ -4601,6 +4601,20 @@ EOD;
         return $this->render($contextheader);
     }
 
+    /**
+      * Renders the header bar.
+      *
+      * @param context_header $contextheader Header bar object.
+      * @return string HTML for the header bar.
+      * @deprecated since 4.5 Please use core_renderer::render($contextheader) instead
+      * @todo MDL-82163 This will be deleted in Moodle 6.0.
+      */
+    #[\core\attribute\deprecated('core_renderer::render($contextheader)', since: '4.5', mdl: 'MDL-82160')]
+    protected function render_context_header(context_header $contextheader) {
+        $context = $contextheader->export_for_template($this);
+        return $this->render_from_template('core/context_header', $context);
+    }
+
     /**
      * Renders the skip links for the page.
      *