[Vue Intl] Cannot format message: "ConstantStrings.zim", using message id as fallback.

[bjester]

Observed behavior

There's a missing string for the ZIM content type

Expected behavior

We add strings so that all content types are represented, even a less common one like ZIM

User-facing consequences

They see ConstantStrings.zim for a UI string

[radinamatic]

There is no string in Studio for ZIM files, but there is one in Kolibri, which means that we can easily recycle the needed translations if necessary 😉