Various improvements for v0.1

[JohannesMeierSE]

Beyond improving comments, refactorings, polishing and so on, these notable improvements are done in this PR:

• functions and operators can be annotated with validations now (review: should we support that for all our types?)
• Typir module:
  • reorganized the grouping of services
  • don't merge Langium+Typir services, but provide the Typir services via an "typir"-property/service within the Langium services
  • override only selected services of a group
  • extracted missing service interface
  • extracted logic to resolve TypeSelectors into its own service to make the implementation exchangable
  • the module now looks into the kind registry, whether the kind is already initialized, before a new one is created (this partially fulfills Integrate remaining types into the factory API #44)
• removed dependencies to 'langium/lsp' from Typir-Langium in order to use it also in non-LSP projects
• switched to Langium v3.3, simplified API, removed duplicated code for a fix which is part of Langium 3.3 now
• added missing READMEs, ChangeLog, added content, added EclipseCon slides
• associate domain elements with Typir types
• implemented overloaded functions and methods in LOX by using Typir already during Linking!
• reduced code for the "Tiny Typir" example a bit

Hints for the review

• Sorry for the huge number of changes!
• Therefore, I suggest to review commit by commit.
• Feel free to ask for a joint review session!

[insafuhrmann]

Thanks for this big lot of improvements @JohannesMeierSE. They look fine to me, I just have a few detail remarks.

[insafuhrmann]

Thanks for the improvements, looks fine to me!