Feature: #96730 - Simplified ext:backend ModuleTemplate API

See Issue #96730

Description

Extensions that deliver own backend modules can now use the TYPO3\CMS\Backend\Template\ModuleTemplate class as view for the ‘body’ part of the view and do not need to instantiate an own view anymore.

The default document header of ModuleTemplate can be rendered using a new fluid layout named Module.

Impact

The standard code within backend module related controllers looked like this until now:

$moduleTemplate = $this->moduleTemplateFactory->create($request);
$view = GeneralUtility::makeInstance(StandaloneView::class);
$view->setTemplateRootPaths(['EXT:my_extension/Resources/Private/Templates']);
$view->assign('aVariable', 'aValue');
$moduleTemplate->setContent($view->render('MyTemplate'));
return $this->responseFactory->createResponse()
    ->withHeader('Content-Type', 'text/html; charset=utf-8')
    ->withBody($this->streamFactory->createStream($moduleTemplate->renderContent($templateFileName)));

This can be streamlined as shown below. Template paths (Templates, Layouts, Partials) are configured automatically, calling renderResponse('SomeController/SomeAction') will look for file Resources/Private/Templates/SomeController/SomeAction.html. Templates can be overridden by other extensions using TsConfig, see this changelog entry for details on this.

$moduleTemplate = $this->moduleTemplateFactory->create($request);
$moduleTemplate->assign('aVariable', 'aValue');
return $moduleTemplate->renderResponse('MyTemplate');

The HTML template should then reference the ModuleTemplate layout:

<html xmlns:f="http://typo3.org/ns/TYPO3/CMS/Fluid/ViewHelpers" data-namespace-typo3-fluid="true">
<f:layout name="Module" />
<f:section name="Content">
    My body content
</f:section>
</html>