Provide `jsonschema` for the Metadata

[Fokko]

Feature Request / Improvement

Iceberg is implemented in more and more languages, and I was wondering if it would be beneficial to create a jsonschema to validate the metadata.

Query engine

None

[github-actions]

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[github-actions]

This issue has been closed because it has not received any activity in the last 14 days since being marked as 'stale'