Set X-ClickHouse-Timezone HTTP response header to the server's timezone

[traceon]

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Changelog category:

• New Feature;

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):
From now on, HTTP responses will have X-ClickHouse-Timezone header set to the same timezone value that SELECT timezone() would report.

executeQuery() callbacks set_content_type_and_format and set_query_id were combined into one set_result_details callback that is expected to accept 4 string arguments: query id, content-type, format, and timezone.

Motivation: ODBC driver, when reading data in ODBCDriver2 format (strings), needs to know the Date's and DateTime's exact timezone, to be able to convert dates correctly. Similarly, when reading data in RowBinaryWithNamesAndTypes format (epoch-based integers), to be able to display Date and DateTime the same way as the clickhouse-client does by default, ODBC driver needs to convert epoch-based integers to server's timezone.