[FEATURE] Add close button with returnUrl in page layout module

Show close button in page layout view if query parameter returnUrl is
set. This can then be used in EXT:brofix (and other extensions) to
pass the returnUrl and the user can jump back by clicking the close
button.

Resolves: #22

Classes/Xclass/PageLayoutControllerWithCallouts.php

@@ -16,7 +16,11 @@
  * The TYPO3 project - inspiring people to share!
  */
 
+use Psr\Http\Message\ServerRequestInterface;
 use TYPO3\CMS\Backend\Controller\PageLayoutController;
+use TYPO3\CMS\Backend\Template\Components\ButtonBar;
+use TYPO3\CMS\Core\Imaging\Icon;
+use TYPO3\CMS\Core\Imaging\IconFactory;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
 use TYPO3\CMS\Fluid\View\StandaloneView;
 
@@ -55,4 +59,31 @@ protected function generateMessagesForCurrentPage(): string
 
         return $content;
     }
+
+
+    /**
+     * @param ServerRequestInterface $request
+     * @return void
+     *
+     * credit: based on Stack Overflow answer https://stackoverflow.com/a/78319234/2444812
+     * by Mogens https://stackoverflow.com/users/5023204/mogens
+     */
+    protected function makeButtons(ServerRequestInterface $request): void
+    {
+        parent::makeButtons($request);
+
+        $returnUrl = $request->getQueryParams()['returnUrl'] ?? '';
+        if (!$returnUrl) {
+            return;
+        }
+
+        $returnButton = $this->buttonBar->makeLinkButton()
+            ->setHref($returnUrl)
+            ->setTitle($this->getLanguageService()->sL('LLL:EXT:core/Resources/Private/Language/locallang_core.xlf:labels.close') ?: 'Close')
+            // Create your custom icon or use any of the alredy created icons
+            ->setIcon($this->iconFactory->getIcon('actions-close', Icon::SIZE_SMALL))
+            ->setShowLabelText(true);
+        // should use BUTTON_POSITION_RIGHT, but does not work?
+        $this->buttonBar->addButton($returnButton, ButtonBar::BUTTON_POSITION_LEFT, 0);
+    }
 }