* Replace external_trigger check with DagRunType

- Fix test_handle_multiple_columns_unique_constraint_error

- Resolve ashb code review

- Add newsfragment

- Replace external_trigger is False logic with run_type is SCHEDULED

- Fix _emit_true_scheduling_delay_stats_for_finished_state

- Fix migrations fix after rebasing to latest main

Fix test_exceptions and static check after rebasing

Fix test_dag_run and erd static check

* fixup! Fix run_type logic, remove unused externally_triggered_type

* fixup! Restore external_trigger value when downgrade

* Remove externally_trigger reference in frontend

The 'triggered_by' field used to only be shown when the run is
externally triggered. Rather than using run_type to maintain the
conditional, I decided to render the field unconditionally instead,
since the value could be useful for scheduler-created runs too (for
example, distinguishing whether a run is asset-triggered or
time-scheduled).

* docs(newsfragments): add migration rules

---------

Co-authored-by: Tzu-ping Chung <[email protected]>
Co-authored-by: Wei Lee <[email protected]>

* Replace external_trigger check with DagRunType

- Fix test_handle_multiple_columns_unique_constraint_error

- Resolve ashb code review

- Add newsfragment

- Replace external_trigger is False logic with run_type is SCHEDULED

- Fix _emit_true_scheduling_delay_stats_for_finished_state

- Fix migrations fix after rebasing to latest main

Fix test_exceptions and static check after rebasing

Fix test_dag_run and erd static check

* fixup! Fix run_type logic, remove unused externally_triggered_type

* fixup! Restore external_trigger value when downgrade

* Remove externally_trigger reference in frontend

The 'triggered_by' field used to only be shown when the run is
externally triggered. Rather than using run_type to maintain the
conditional, I decided to render the field unconditionally instead,
since the value could be useful for scheduler-created runs too (for
example, distinguishing whether a run is asset-triggered or
time-scheduled).

* docs(newsfragments): add migration rules

---------

Co-authored-by: Tzu-ping Chung <[email protected]>
Co-authored-by: Wei Lee <[email protected]>

…context key for Airflow 3.0 (`AIR301`) (#22850)

## Summary

<!-- What's the purpose of the change? What does it do, and why? -->
Context:
apache/airflow#41641

1. apache/airflow#45961
* <strike>create_dagrun removed from airflow...DAG</strike> (This has
already been implemented in AIR301)
* context key dag_run.external_trigger removed
2. apache/airflow#45960
* context["inlet_events"]["url"] → context["inlet_events"][Asset("url")]
3. apache/airflow#41348
* context key triggering_dataset_events → triggering_asset_events

The existing AIR301 rules can detect when users access a removed key
such as `execution_date` through Airflow's `context`. For example,
`context["execution_date"]`, or `context["dag_run"]`. However, if an
attribute is deprecated from a context key, such as
`context["dag_run"].external_trigger`, the current implement will not
flag it.

This PR adds the logic for such check, and add two rules to flag the
deprecated attribute for the `"dag_run"` and `"inlet_events"` context
key. In addition to this, `"triggering_dataset_events"` is a deprecated
context key which can be handled by the existing rule. However, the
existing rule doesn't raise a diagnostic. Hence, the rule logic is
refactored a little bit, such that we can add this check and suggest a
`Replacement::Rename`.

## Test Plan

<!-- How was it tested? -->
The test cases have been added to `AIR301_context.py`, and all the tests
have been run locally and success. @Lee-W , could you please review it
when you have time, thanks!

## Notes

In #22376, we introduced some
improvements to the AIR301 code. I will re-base this PR when we are all
good on that, so it can pick up those code structure improvements, and
updated rules.