Rewrite playground in Gleam about gleam-playground

[JohnDoneth]

gleam-vdom is still missing required features like persisting event handlers between updates, components / hooks, and reference handling to external DOM elements before it can be used to write a nice framework on top. I can open some issues on that repository for tracking the previously mentioned items.

Other than that. There will also be the task of wrapping the JavaScript libraries currently used by the playground right now with Gleam. I foresee Monaco being the most time consuming. We don't have to write a wrapper for the entire library, just the pieces we need for now.