Feature: #71251 - Add FlashMessage support in ModuleTemplate API

See Issue #71251

Description

Flash messages have different queues, depending on in which context they are enqueued. The FlashMessageService defaults the queue to core.template.flashMessages , Extbase defaults the queue to extbase.flashmessages .$randomPluginQueue .

Support for flash messages in ModuleTemplate has been added to enqueue flash messages automatically in the correct queue identifier.

Impact

Flash messages can be enqueued by the following code:

$this->moduleTemplate->addFlashMessage('I am a message body', 'Title', \TYPO3\CMS\Core\Messaging\AbstractMessage::OK, true);