Add default_format setting

[slvrtrn]

Description

This PR adds the missing default_format setting and an example of how to use it.

Checklist

• [x] Unit and integration tests covering the common scenarios were added
• [x] A human-readable description of the changes was provided to include in CHANGELOG

[mshustov]

can be also specified as a parameter https://github.com/ClickHouse/clickhouse-js/issues/198