homogenize delayed annotation evaluation in all files

[fzimmermann89]

Might be useful for consistency to always from __future__ import annotations

This can be done using ruff:

[tool.ruff.lint.isort]
required-imports = ["from __future__ import annotations"]

@schuenke : what do you think?

..or only do it when it is really required. currently, we do it in a lot of random files.

[schuenke]

do we still need it when we use the from typing import Self style?

[fzimmermann89]

..or remove them from all files and see where we actually need them.