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)

Start by reading airflow/config_templates/config.yml to understand the existing metadata for airflow.cfg options and how it could be represented as a JSON schema. Done means publishing an equivalent schema and, eventually, making it suitable for submission to schemastore.org; no specific test file is named.

Written by the indexing model from the issue text.