Feature: #80374 - Add generic fluid template for already rendered content

See Issue #80374

Description

To provide better support for content elements where the content itself is not processed by fluid we introduce a new generic template, to make it easy to benefit from the universal layouts of fluid styled content.

The generic template only wrapps already generated html that have been assigned to the variable content. This eliminates the need for extensions to provide custom templates to wrap their external rendered content to achieve the same behaviour as other fluid styled content elements.

Template

<html xmlns:f="http://typo3.org/ns/TYPO3/CMS/Fluid/ViewHelpers" data-namespace-typo3-fluid="true">
<f:layout name="Default" />
<f:section name="Main">
   <f:comment>This templates is used to provide nessesary functionality for external processed content and could be used across multiple sources, for example the frontend login content element.</f:comment>
   {content -> f:format.raw()}
</f:section>
</html>

Example Usage

tt_content.mycontent =< lib.contentElement
tt_content.mycontent {
   templateName = Generic
   variables {
      content = USER_INT
      content {
         userFunc = ACME\ContentExtension\Controller\SuperController->main
      }
   }
}