Deprecation: #73511 - BrowserLanguage detection moved to Locales 

See forge#73511

Description 

The CharsetConverter contained the calculation to find the corrent language based on the browsers language settings at the backend login screen.

The according code has been moved to TYPO3CMSLocalizationLocales. The method CharsetConverter::getPreferredClientLanguage() and the property CharsetConverter::charSetArray have been marked as deprecated.

Impact 

Calling CharsetConverter::getPreferredClientLanguage() will trigger a deprecation log entry.

Affected Installations 

All installations with a third-party extension using the CharsetConverter language resolving directly.

Migration 

Use the method Locales->getPreferredClientLanguage() instead.