Support deferring from taskflow tasks

### Body

could be cool

you just have to make it so that the function gets re-entered

then you could have something like

```python
@task
def my_deferrable(event=None):
if event:
do something
else:
do something and then defer
```

There have been other ideas, doing something with yield

cc @uranusjr since we chatted about it at one point

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.

Start with the TaskFlow @task entry point and review how deferrable tasks are currently represented. Define and document the expected re-entry behavior, including how an event reaches the task after deferral, then verify the proposed approach against the example in the issue.

Written by the indexing model from the issue text.