Shuffle layout in story galleries

Recently we've had some questions about changing the layout of gallery images in the New Story Editor. It turns out that not many people are aware that the order of uploaded images affects the layout and ordering can be changed in the upload modal.

`Shuffle layout` button

Say hello to the new "Shuffle images" button that lets you try out a random layout of the gallery with a single click. The more images a gallery has, and more they vary in aspect ratios, the more this feature should be useful.