The Svelte code should not have custom logic for the Gin theme

Started this but wasn't quite able to remove all mentions of Gin from the Svelte code, since we're also using it to conditionally apply classes to elements. Not entirely sure how to approach fixing that.

This is ready for an initial round of review.

Unfortunately, I don't think switching from 'gin' in drupalSettings to GIN_ENABLED gains us anything -- the problem still exists, which is that we are conditionally applying classes based on the presence of the Gin theme. We need to not do that. The goal is for the Svelte code to not mention or care about Gin at all.

Let's maybe talk through the CSS cascade here and see what we can do about it.

moving back to NW for now

phenaproxima → closed merge request !700

Couple of questions but this seems like a big improvement to me.

I have moved the css related to Gin into it's specific file.This is ready for review.

Should probably get some manual testing but I think this looks like great and worthwhile cleanup!

Saving credit

Merged !769 🎉

Automatically closed - issue fixed for 2 weeks with no activity.