Feature: #78672 - Introduce fluid data processor for menus

Description

This menu processor utilizes HMENU to generate a json encoded menu string that will be decoded again and assigned to FLUIDTEMPLATE as a variable. Additional DataProcessing is supported and will be applied to each record.

Options: as The variable to be used within the result levels Number of levels of the menu expandAll If false, submenus will only render if the parent page is active includeSpacer If true, the doctype "Spacer" will be included in the menu titleField Field that should be used for the title

See HMENU docs for more options. https://docs.typo3.org/typo3cms/TyposcriptReference/ContentObjects/Hmenu/Index.html

Example TypoScript configuration:

10 = TYPO3\CMS\Frontend\DataProcessing\MenuProcessor
10 {
   special = list
   special.value.field = pages
   levels = 7
   as = menu
   expandAll = 1
   includeSpacer = 1
   titleField = nav_title // title
   dataProcessing {
      10 = TYPO3\CMS\Frontend\DataProcessing\FilesProcessor
      10 {
         references.fieldName = media
      }
   }
}