Port BO Avis to BO4E-python

[hf-kklein]

• Port our own (Hochfrequenz) Business Object Avis to Python.
  • create an avis.py in bo4e-python: https://github.com/bo4e/BO4E-python/tree/main/src/bo4e/bo
  • run tox and create dev environment (see python template repository)
  • port all the properties from the c# avis class (link above) to the new class in bo4e-python
    • create missing coms and enums in BO4E-python
• Add tests (to the python implementation) as usual
• Put focus on a well documented data model (docstrings). Ask for help if necessary.
• If the CI passes let someone from the Hochfrequenz team review it
• Do not merge it to bo4e/BO4E-Python yet! We want to use th BO Avis to establish a git based workflow to enhance the official BO4E standard (meaning: someone from another company with functional knowledge should review it)

fyi @hf-krechan

[hf-kklein]

Ah, das hat Daniel schon gemacht 🙈
bo4e/BO4E-python#522