[TASK] Fixing tremplates not found issue when having controller in backend folder

Classes/Controller/BackendController.php

Classes/ViewHelpers/AbstractViewHelper.php

Classes/ViewHelpers/AddJavaScriptFileViewHelper.php

Classes/ViewHelpers/InlineLanguageLabelsViewHelper.php

Configuration/TypoScript/Backend/constants.txt

Configuration/TypoScript/Backend/setup.txt

Resources/Private/Layouts/Backend.html

Resources/Private/Partials/ButtonBar.html

Resources/Private/Templates/Backend/Index.html

ext_localconf.php

ext_tables.php