Support INSERTs into system.zookeeper table

Why it matters

This feature enables users to write data directly into the system.zookeeper table, allowing for easier manipulation and management of ZooKeeper data within ClickHouse. It addresses the limitation of only being able to read from this system table and facilitates more flexible interaction with ZooKeeper nodes.

How to use it

Users can perform INSERT statements targeting the system.zookeeper table like any other table in ClickHouse. For example:

INSERT INTO system.zookeeper (path, data) VALUES ('/example_path', 'example_data');