Feature: #85164 - Enable Languages on a per-site basis

See Issue #85164

Description

When configuring a new site with multiple languages, is it now possible to not allow a language to be rendered in the TYPO3 Frontend. A new checkbox in the Site Handling module allows to add a language but not render it in Frontend to allow to prepare a new translation of a website before it is going live.

Impact

Going live with a new language is now as easy as turning on one checkbox.