Add decorators for external and venv python branching operators

[jscheffl]

This PR is a follow-up of PR #33356 to add also python decorators for additional branching tasks for:

• external python
• python virtual environments
  To make the feature set complete also for taskflow style DAGs.

How to test?

• See docs and in general CI is green
• Run the example_branch_operator
• Run the example_branch_python_operator_decorator

[potiuk]

Looks really nice. But how about adding Howtos/Examples to https://airflow.apache.org/docs/apache-airflow/stable/howto/operator/python.html folllowing other operators? I think otherwise they will not be easily discoverable

[jscheffl]

Looks really nice. But how about adding Howtos/Examples to https://airflow.apache.org/docs/apache-airflow/stable/howto/operator/python.html folllowing other operators? I think otherwise they will not be easily discoverable

Good idea... should have had the idea myself with examples... DIFF is larger now. I re-worked the existing branching examples and made it all together in one place - let me know if this was the correct idea.
See in "How to test" which DAGs as example are modified now. Also made this for the classic operators for consistency.

[potiuk]

tests need fixing but It LGTM otherwise.

[potiuk]

All Good. Failed check fixed in main,