EZP-22464: Referenced SiteAccesses by language at compile time
EZP-22464: Added RouteReference concept

RouteReference work like ControllerReference. It represents a route, with its resource and params,
but it's easy to modify at runtime.
The RouteReferenceGenerator gives an opportunity to alter the generated RouteReference by dispatching a
dedicated event.
EZP-22464: Implemented ez_route() Twig function
EZP-22464: Added getTranslationSiteAccess() in TranslationHelper
EZP-22464: Unset "viewType" and "layout" parameters in UrlAliasRouter

This is to avoid them to appear when generating a link with a RouteReference.
EZP-22464: Added LanguageSwitchListener

To be triggered on RouteReference generation
EZP-22464: Handle multi-lingual URLAliases when switching siteaccess on link generation
EZP-22464: Exposed ezpublish.translationSiteAccess() Twig helper
EZP-22464: Implemented TranslationHelper::getAvailableLanguages()
EZP-22464: Exposed ezpublish.availableLanguages() Twig helper
EZP-22464: Added tests to GlobalHelper
EZP-22464: Added specification
EZP-22464: Fixed missing empty line
EZP-22464: Removed unneeded array initialization
EZP-22464: Added more description to LanguageSwitchListener
EZP-22464: Adapt URLAliasService::listLocationAliases() call to comply #835

See https://jira.ez.no/browse/EZP-22803
EZP-22464: Fixed tests
EZP-22464: Added tests for EzPublishCoreExtension
EZP-22464: Added test for UrlAliasGenerator
EZP-22464: Added doc for the RouteReference concept