Feature: #71196 - Disallow localization mixtures

See Issue #71196

Description

The PageLayout UI will now inform users if a mixture of translated content and standalone content is used in the page module since this is a major source of confusion for both administrators and editors.

In case an integrator knows what he/she is doing, we introduce a PageTSConfig setting to turn these warnings off to allow further usage of inconsistent translation handling.

mod.web_layout.allowInconsistentLanguageHandling = 1

Impact

Upon setting mod.web_layout.allowInconsistentLanguageHandling to 1 the page module will behave as before and allow inconsistent mixups of languages in a certain language.