Add clusterAllReplicas function for querying all cluster nodes

Why it matters

This feature addresses the need to query every node within a ClickHouse cluster including all replicas, rather than just one replica per shard. It ensures comprehensive data retrieval and consistency checking across all replicas, which is valuable for tasks like validation, debugging, and full cluster analytics.

How to use it

Use the clusterAllReplicas table function in your queries to specify the cluster and table you want to query across all nodes. For example:

SELECT * FROM clusterAllReplicas('cluster_name', 'database_name', 'table_name')

This will run the query on every replica in the specified cluster.