App config
The expressjs application has two application contexts: the context running on the server (SSR) and the context executed in the browser.
Server context: Most configuration options can be shared between executions (different requests from different users), but we need to make sure that axiosBackend
is not misconfigured or shared between user requests. The i18nServer and its configuration need to be instantiated for every request.
The client context is a single user context (in the browser) and we don't need to worry about it after the initial setup.