[IDEA] - Configuration File as JSON

Change the configuration.ini to configuration.json

With this, we can do jerarquization, and add a json-schema to validate the syntax of the configuration.

Also, access to the configuration should be done with a Singleton.

Another enchancement can be make a callback onChange.
So changes in the configuration will not require restart of CKAN

Begin in the main CKAN repository or its Discussions, since this ideas repository is deprecated. Locate configuration.ini and the existing configuration access entry point, then establish whether JSON migration, schema validation, Singleton access, and on-change reload are all in scope. Done requires an agreed design and tests for the selected behavior.

Written by the indexing model from the issue text.