Publish JSON schema for airflow.cfg

### Description There is already a good structured YAML file providing metadata about all valid configuration options in `airflow.cfg`: [airflow/config_templates/config.yml](https://github.com/apache/airflow/blob/9c4b81d71f3caee3a3b1c6d9c626ee5d16f0db7c/airflow/config_templates/config.yml). I think publishing the same data as a JSON schema and eventually to https://www.schemastore.org/json/ could be very useful. ### Use case/motivation - People could use extensions like [Even Better TOML](https://marketplace.visualstudio.com/items?itemName=tamasfe.even-better-toml) with their IDE to benefit from validation and powerful auto-completion while editing `airflow.cfg` - It would be easy to leverage pre-commit hooks or other CI tools to catch mistakes in the config file. Airflow won't complain if the configuration file contains a typo or a non-existent configuration key making it easy to make mistakes. It could also make it easier to catch invalid values earlier. ### Related issues _No response_ ### 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)