[experimental] Add official SolidJS adapter maintained by community

Hi mates 👋

I’ve built [dnd-kit-solid](https://github.com/kachurun/dnd-kit-solid) – a SolidJS adapter for @dnd-kit/dom, fully aligned with the structure and API of the React version (@dnd-kit/react). It supports all the core features and provides Solid-friendly hooks and components. I'm also planning to add extra components like Draggable, Droppable, and Sortable.

I’d love to contribute it directly to this repo under an @dnd-kit/solid package (similar to how @dnd-kit/react is structured), if that’s possible. I’ll take full responsibility for maintaining it and keeping it up to date with changes in the core.

Let me know what you think! I'd be happy to open a PR if you're open to the idea 🙏