Airflow API for 'airflow dags reserialize'

### Description An Airflow API endpoint to programatically reserialize dags, aligned with the `airflow dags reserialize `CLI command: https://airflow.apache.org/docs/apache-airflow/stable/cli-and-env-variables-ref.html#reserialize ### Use case/motivation Currently, I must exec into my Airflow webserver in order to run the CLI command to refresh dags. However, I already have an Airflow client programatically communicating to the Airflow webserver API. It would be great to be able to request the API to refresh dags when required. As a temporary solution, I have set a low interval of 1s for: - min_serialized_dag_update_interval - min_serialized_dag_fetch_interval But have found high constant resource usage as a result to the Airflow services. ### Related issues An extension of https://github.com/apache/airflow/issues/19432 ### Are you willing to submit a PR? - [ ] Yes I am willing to submit a PR! ### Code of Conduct - [x] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)