mark dag_run and ti as automatically injected

[ZeeD]

Allow the usage of the mypy plugins to typecheck the @task annotated tasks. With this change it will be possible to avoid mypy complains when definiing a task like in https://airflow.apache.org/docs/apache-airflow/stable/tutorial/taskflow.html#accessing-context-variables-in-decorated-tasks with ti as an automatically injected parameter.

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