Refactor project to use SvelteKit's packaging

[vatro]

• Follow official recommendation and switch to SvelteKit / packaging:
  see Add a TypeScript component template  sveltejs/component-template#29 (comment)
  see https://kit.svelte.dev/docs#packaging
• Eventually / if needed : change project structure / eliminate all circular dependencies -> internal module pattern
• Close Replace SvelthreeAnimation component with a class #55
• Make components generator more granular in order to be able to easily exclude unneeded imports and log-vars (verbose mode)

[vatro]

This didn't work out smoothly as I was hoping.

What I didn't like:

• (not severe) Svelte files inside the package are heavy reformatted -> can be fixed? (I guess)
• (not severe) Exporting types from Svelte components seems to be broken:
  exported types get removed from <script context="module">...</script> and are double-added (!?) to component.d.ts:
  could be fixed by removing all exported types from components, but it feels wrong, because it should work out of the box.
• (bug?) empty <script context="module"> </script> blocks in *.svelte files (after removal of exported types) throw an error:

  Type '{ context: string; }' is not assignable to type 'HTMLProps<HTMLElement>'.
    Property 'context' does not exist on type 'HTMLProps<HTMLElement>'. Did you mean 'content'?js(2322)
  

  <script context="module"> </script> should be removed when empty -> report?
• (severe) inside component.d.ts file the component class is named exactly the same as the imported 'three' class:
  could be fixed by e.g. import { AmbientLight as THREE_AmbientLight } from "three", but I would have to change a lot, and I'm quite sure there would be other negative side-effects with different builds etc.

I'm not sure if using SvelteKit's packaging is not suitable for the project, but I've decided to got with the currently working solution and get back to tweaking this setup later.