Improve Enum construction

[hf-krechan]

At the moment the enums are generated during runtime. This is now fine cause it works, but your IDE of choice is not able to make suggestions in this way.
It should be like the HTTPStatus enum

from http import HTTPStatus

HTTPStatus.ACCEPTED

The main struggle is the string representation for the serialization. But this issue should be solveable.

[hf-kklein]

If we decide to use Python 3.10, this problem should be solved by using StrEnum:
https://github.com/python/cpython/blob/7c4d96103c4e16161e9aed9a584c9857d0674099/Doc/howto/enum.rst#id101

https://docs.python.org/3.10/whatsnew/changelog.html#changelog
https://bugs.python.org/issue41816