Access reporter + JSON Schema generator

A cool feature would be an access reporter that accumulates the keys and types that were read by an access reporter, and emit a JSON Schema that describes that structure.

An app developer can then run this to generate the JSON Schema ones, check it into their repo, and add the JSON Schema link as a comment to their JSON/YAML config file, and many IDE plugins then provide autocompletion and validation.

No files, tests, or entry points are named. Start by locating the existing access reporter and the configuration handling for JSON/YAML, then determine how accessed keys and types should map to JSON Schema. Done means an app developer can generate a schema from an access reporter for IDE validation and autocompletion.

Written by the indexing model from the issue text.