Element Call configured the global i18next singleton. When Element Call
runs embedded in a host application rather than as its own page, that
singleton belongs to the host, so configuring it would clobber the
host's translations.
Create Element Call's own instance in utils/i18n.ts, configure it in the
initializer, and pass it to components via <I18nextProvider>. Drop
.use(initReactI18next) from the initializer: it registers the instance
as react-i18next's global default, which is the global we are trying to
avoid. Tests and stories keep using it, so that they do not need to wrap
every render in a provider.
Two modules imported `t` directly from "i18next" and so were bound to
the global instance: utils/errors.ts now calls i18n.t() on the instance
(reached at call time, since i18next only assigns `t` during init), and
QrCode uses useTranslation() like every other component.
No functional change.
Valere