Added Custom Commands to ClickHouse Keeper Client for Easier Debugging

Why it matters

The new custom commands provide more tools for interacting with ClickHouse Keeper, simplifying the debugging process and improving visibility into the internal state and behavior of ClickHouse clusters.

How to use it

Users can access the new custom commands by running the clickhouse-keeper-client and invoking the added commands as documented. These commands are designed to facilitate diagnostics and troubleshooting directly via the Keeper client interface.