fix: parse customized JSON types as JSON

[Steffen911]

Summary

Fixes #349

Checklist

Delete items not relevant to your PR:

• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided so that we can include it in CHANGELOG later
• For significant changes, documentation in README and https://github.com/ClickHouse/clickhouse-docs was updated with further explanations or tutorials

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[Steffen911]

@slvrtrn Seems like I had a formatting problem that I addresses in the most recent commit. Could you take another look?