feat: pydantic

[Paillat-dev]

Summary

• This is a very early poc
• This has no pretension to get merged
• This is mostly me trying things out here and there
• Give feedback if you want

fixes #2642

The goal is to

• Set up a robust migration system allowing for pydantic and non pydantic types to cohabit.
• Migrate the main types to pydantic models
• Add lots of typing

Information

• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed).
• This PR is not a code change (e.g. documentation, README, typehinting,
  examples, ...).

Checklist

• I have searched the open pull requests for duplicates.
• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• If type: ignore comments were used, a comment is also left explaining why.
• I have updated the changelog to include these changes.