Feature: Add option to use Slick Slider - #6

Looks great!

One thing that came up in one of my impactful story reviews with ATS is that the captions for Slick Slider are not accessible (they are triggered by hovering on a :before which screen readers can't see). Perhaps a future discussion about improving them vs finding an eventual alternative (e.g. we are using Bootstrap's carousel in the storytelling modules plugin).

Another piece of feedback I got on the story plugin is that the captions cover too much of the images on mobile and I think we run into that here too. This is something we're still working on so I'm happy to share what we come up with when we have a solution ready.

I would like to see some kind of navigation arrows on mobile so the user knows there are slides to flip through and it's not just a static image - and realizing they can't take up too much space (same issue as above!).