Feature: #96800 - Add SiteLanguageProcessor

See Issue #96800

Description

A new Data Processor SiteLanguageProcessor has been introduced, which can be used to fetch the properties of the current SiteLanguage within Fluid Templates in TYPO3 Frontend rendering:

tt_content.mycontent.20 = FLUIDTEMPLATE
tt_content.mycontent.20 {
   file = EXT:myextension/Resources/Private/Templates/ContentObjects/MyContent.html

   dataProcessing.10 = TYPO3\CMS\Frontend\DataProcessing\SiteLanguageProcessor
   dataProcessing.10 {
      as = language
   }
}

In the Fluid template the properties of the SiteLanguage entity can be accessed:

<p>{language.languageId}</p>
<p>{language.customValue}</p>