JSON Schema: add linting rules for missing keywords

[char0n]

Not all keywords in our common Schema Object are covered with linting rules.

I've just confirmed that OpenAPI 2.0 and OpenAPI 3.0.x are fully covered.

What's missing is AsyncAPI 2.x (JSON Schema Draft 7) and OpenAPI 3.1.0 (JSON Schema Draft 2020-12).

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As part of this issue, completion and documentation rules should also be reviewed and followup new issues created. It's fully reviewed and complete for OpenAPI 2.0 and partially for OpenAPI 3.0. Other spec (including OpenAPI 3.0) needs to be double-checked.