Super-issue: Rethink / re-design "object-system"

[marzipankaiser]

In general, we need to rethink / redesign the "object-system" anyways. Some aspects are:

• [ ] Mutual recursive objects
  • [x] #274 (globally)
  • [ ] #600 (locally?)
• [ ] toplevel objects (can those be mutually recursive?)
• [ ] classes
• [ ] implementing multiple interfaces
• [ ] objects as members
• [ ] private methods
• [ ] "extension" methods
• [ ] fields

See also

• This is inspired by @b-studios in https://github.com/effekt-lang/effekt/issues/600#issuecomment-2370616782