feat(wit): Restructure the WIT definitions into deps

[celarye]

This is still a WIP, any feedback on the new design/structure is very much appreciated.

• The plugin world is now composed of the core and services worlds.
• Shared types have been exported to the wpbs:shared dependency.
• The services world is composed of all available services.
  • Down the line the implementation of these services will be optional (Optional Imports Phase 1: Tooling Conventions WebAssembly/component-model#555).
• Each service implements the register family of functions itself now.
• Support for dependency functions has been removed, components should compose dependencies themselves (https://component-model.bytecodealliance.org/composing-and-distributing/composing.html).

[celarye]

Versioning was reset, from now these wit package will evolve on their own.

On that note, it's currently not perfect yet either:

• Every time a new service gets added or updated the plugin package needs a bump as well, this is okay but maybe we should make core its own package as well? The reasoning behind this is that a version bump of the plugin package does not mean the core implementation has changed.
• We should add feature gates like @since(version = 0.1.0) or @unstable(feature = fancier-foo) (https://github.com/WebAssembly/component-model/blob/main/design/mvp/WIT.md#feature-gates) to all declarations (interfaces, funcs, ...).