Add EditWithUnique

[kuuak]

https://github.com/superhuit-agency/freerideworldtour.com/pull/531

See hotfix also : https://github.com/superhuit-agency/freerideworldtour.com/commit/855bbd2aa3981feb9d706e485ee7bb1489f521fa => Investigate on how we could combine multiple EditWithXXX HOC components for DRYness

[charl0tee]

We leave this issue on hold for the moment, as we don't see the need to add it to our stack, as it's specific to when we have multiple headers for the same post type. If we see that it seems helpful for most of the projects, we might consider to add it to the stack.