Post model images should be translatable

[viktor-yunenko]

Image can contain text, and at the moment the editor has no choice but to add a global eg German image to all 4 languages.

[viktor-yunenko]

On a WIP project this is an essential feature for me already, hence I'll use a fork and submit a PR in the meantime 👍

[yakky]

Nice! The only caveat here is to keep the process straightforward for single languages too and to ensure a smooth (or transparent) upgrade from current situation