Restore Airflow context in virtualenv operators

[eddiesr93]

Enable PythonVirtualenvOperator and ExternalPythonOperator callables to opt into the current task context through airflow.sdk.get_current_context().

The parent process serializes the supported context fields, and the subprocess restores them with the SDK context manager for the duration of the callable. The option remains disabled by default and validates that Airflow 3 is available in the target environment. This also removes the obsolete AIP-72 test exclusions and documents both operators.

This restores the feature tracked in #46361 now that Airflow 3 context serialization can safely carry the required SDK objects.

Validation:

• uv run --frozen --project providers/standard pytest providers/standard/tests/unit/standard/operators/test_python.py -k 'current_context or use_airflow_context' -q (8 passed)
• uv run --frozen prek --files ... for all changed files

closes: #46361

---

Was generative AI tooling used to co-author this PR?

• Yes — Codex (GPT-5)

Generated-by: Codex (GPT-5) following the guidelines

---

Drafted-by: Codex (GPT-5) (no human review before posting)

[boring-cyborg]

Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide
Here are some useful points:

• Pay attention to the quality of your code (ruff, mypy and type annotations). Our prek-hooks will help you with that.
• In case of a new feature add useful documentation (in docstrings or in docs/ directory). Adding a new operator? Check this short guide Consider adding an example Dag that shows how users should use it.
• Consider using Breeze environment for testing locally, it's a heavy docker but it ships with a working Airflow and a lot of integrations.
• Be patient and persistent. It might take some time to get a review or get the final approval from Committers.
• Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Mailing list and Slack.
• Be sure to read the Airflow Coding style.
• Always keep your Pull Requests rebased, otherwise your build might fail due to changes not related to your commits.
  Apache Airflow is a community-driven project and together we are making it better 🚀.
  In case of doubts contact the developers at:
  Mailing List: dev@airflow.apache.org
  Slack: https://s.apache.org/airflow-slack