[PHP-WEBMASTER] [web-php] PR #1121: Replace languages.inc globals with I18n\Languages consts

Pull Request: Replace languages.inc globals with I18n\Languages consts by MauricioFauth · Pull Request #1121 · php/web-php · GitHub
Author: MauricioFauth

The include/languages.inc file was not removed as it's used in other repositories. It should be removed after migration.

Tests were added to ensure that the global variables and the constants are in sync with each other.