Generate database ERD using chartdb

### Body https://github.com/chartdb/chartdb is very popular project and generate nice ERD schemas (~though not sure if we can use it due to AGPL-3.0 license ?~) We should update our [generation script](https://github.com/apache/airflow/blob/3f6f04868d09a8766e4652417b7c0e8082ca2fd7/scripts/in_container/run_prepare_er_diagram.py) to use it Note: This library is to be used only for development. We are not distributing it to users thus we are OK with having it despite AGPL-3.0 license https://www.apache.org/legal/resolved.html#prohibited (Thanks to Jarek for this clarification) ### Committer - [x] I acknowledge that I am a maintainer/committer of the Apache Airflow project.