sideload translations to show preview in current user locale

While investigating this Zendesk ticket (https://support.zendesk.com/agent/#/tickets/723043) I noticed that we're not sideloading translations. We show translated content (line 98) so we need to sideload.

Unfortunately this won't fix the original issue I linked to, it's a help center API bug.

@maximeprades @princemaple @ryanseddon