Feature: #90115 - Add support for Kinyarwanda language

See Issue #90115

Description

Kinyarwanda - the Rwanda official language is now available to use in TYPO3 system-wide for translation labels, giving full support for having a TYPO3 installation (Frontend and Backend) working with Kinyarwanda out-of-the-box.

The ISO-639-1 language code “rw” is now added to TYPO3’s default locales.

Impact

Kinyarwanda will be shown on the “Manage Language Packs” modal and also possible to select in BE user preferences. It is possible to use the “kw” ISO-639-1 iso code in site languages to use the labels in TYPO3 Frontend.