[Routes] Remove JMSi18nRoutingBundle
Proposal: remove JMSi18nRoutingBundle in favour of Symfony's native system; actually this fork is already an updated and shrinked version - see it's readme file; see also symfony/symfony#30617 and https://github.com/symfony/symfony/commit/e46495499841f805ab1915643f763d736d24822e
Remaining blocker: the native system in Symfony does not support externalised translations yet.
https://github.com/php-translation/symfony-bundle/issues/212
See also https://github.com/zikula/core/blob/d8824b4b0f9a056090fadb28166f819afec469e3/src/system/ThemeModule/EventListener/DefaultPageAssetSetterListener.php#L138-L143 (commented code is temporarily removed from master)
Symfony issue: https://github.com/symfony/symfony/issues/30098
https://symfony.com/blog/new-in-symfony-5-1-different-hosts-per-locale