Docs: Schema generation

[s1ntaxe770r]

🧠 Ai UsageDetails (if applicable):

This pr adds a schema sub command to enable dgctl generate a jsonschema for digger.yml config files , as requested in #2541

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[emersonf-cat]

@s1ntaxe770r to clarify, my suggestion was to be "contract first". In other words, creating and maintaining a JSON Schema file by hand for the configuration, which is then used to generate code and documentation. Not generating the schema from documentation or code.

JSON Schema will help you be deliberate about configuration files and their changes, and with appropriate tooling, keep your documentation always in sync. It also lets you implement commands like validate to check if Digger config files are valid, and failing fast if they're not.