Expose full response headers object

[slvrtrn]

Summary

It is now possible to get the entire response headers object from the query/insert/command/exec methods. With query, you can access the ResultSet.response_headers property; other methods (insert/command/exec) return it as parts of their response objects as well.

For example:

const rs = await client.query({
  query: 'SELECT * FROM system.numbers LIMIT 1',
  format: 'JSONEachRow',
})
console.log(rs.response_headers['content-type'])

This will print: application/x-ndjson; charset=UTF-8. It can be used in a similar way with the other methods.

Checklist

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

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
93.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[mshustov]

It's the first HTTP abstraction that leaks in the result set. I'd rather add some generic method to avoid a breaking change once TCP protocol is supported, but your call

[slvrtrn]

I think it is already leaking a bit, as we allow text/json calls, which are not very compatible with Native and even RowBinary format; in time, we will likely have to implement the native version with a new result set flavor (similarly to RowBinary).