AIP-84 Migrate the public endpoint Get DAG Source to FastAPI #42876

Description

Currently the Get DAG Source public endpoint is at api_connexion/endpoints/dag_source_endpoint.py under get_dag_source. We need to migrate it to the api_fastapi/views/public/dag_sources.py under a get_dag_source or similar.

Features and functionality of the endpoint will remain unchanged.

Use case/motivation

AIP-84 cWiki Link: https://cwiki.apache.org/confluence/display/AIRFLOW/AIP-84+UI+REST+API

Related issues

Related to: #42370

Are you willing to submit a PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct