Integrations: code blocks from external repos improvements

[Blargian]

Summary

A few changes to external code block functionality:

• make use of URL parsing library
• add list of whitelisted repositories
• only accept code from raw github

CC @laeg, as discussed. Will follow up to move this to a GH action.

Checklist

• Delete items not relevant to your PR
• URL changes should add a redirect to the old URL via https://github.com/ClickHouse/clickhouse-docs/blob/main/docusaurus.config.js
• If adding a new integration page, also add an entry to the integrations list here: https://github.com/ClickHouse/clickhouse-docs/blob/main/docs/integrations/index.mdx

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Project	Deployment	Preview	Comments	Updated (UTC)
clickhouse-docs	Error			Nov 13, 2025 5:18pm

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Project	Deployment	Preview	Comments	Updated (UTC)
clickhouse-docs-ru	Ignored	Preview		Nov 13, 2025 5:18pm
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