Provide JSON Schema for config file about artifactory-cleanup

[allburov]

I like the idea!

The problem that I've met before with JSON schema - it doesn't support types based on property value.
For instance

• the rule Repo only allows field repo
• PropertyEq - fields property_key and property_value

- rule: Repo
  name: repo.snapshot

- rule: PropertyEq
  property_key: key-name
  property_value: 1

We need to look at rule value to determine the applied schema for the object.

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While I was typing it, I found recent solution for that - https://json-schema.org/understanding-json-schema/reference/conditionals.html.

Feel free to contribute such generator!
I think we shouldn't contribute just a single json-schema, but provide a script for these who created their own rules.