Add elapsed_ns field to HTTP headers X-ClickHouse-Progress and X-ClickHouse-Summary

Why it matters

This feature provides precise timing information by including the elapsed time in nanoseconds in the HTTP progress and summary headers. It helps users monitor query execution duration more accurately, enhancing performance analysis and debugging capabilities.

How to use it

When making HTTP requests to ClickHouse, inspect the X-ClickHouse-Progress and X-ClickHouse-Summary headers to find the elapsed_ns field, which reports the elapsed time in nanoseconds. No additional configuration is needed as the field is included by default.