[dev] Nouveau composant chat, basé sur converse.js

Integration code : <ldp-chat data-authentication="anonymous" data-auto-login="true" data-bosh-service-url="https://conversejs.org/http-bind/" data-debug="true" data-jid="nomnom.im" data-locales-url="https://cdn.conversejs.org/locale/{{{locale}}}/LC_MESSAGES/converse.json", data-room-jid="anonymous@conference.nomnom.im">