**Describe the solution you'd like**

We already can run clickhouse-server without configured ZooKeeper (the tables will start in read-only mode)
and with configured ZooKeeper, if it starts to be inaccessible at runtime (the tables will be read-only until the session is re-established).

Let's also make it possible to start up when ZooKeeper is unavailable.

**Additional context**

If that will be very hard to implement, we can consider other options:
- lazy attaching of the tables after sever start-up;
- a maintenance mode when the tables are not attached at start-up and require manual ATTACH queries.
ErrorCodes::NOT_IMPLEMENTED);
    }
    assert(renaming_restrictions == RenamingRestrictions::ALLOW_PRESERVING_UUID);
    if (!new_name.hasUUID() && getStorageID().hasUUID())
        throw Exception("Cannot move Replicated table to Ordinary database, because zookeeper_path contains implicit 'uuid' macro. "
                        "If you really want to rename table, "
                        "you should edit metadata file first and restart server or reattach the table.", ErrorCodes::NOT_IMPLEMENTED);
}
void StorageReplicatedMergeTree::rename(const String & new_path_to_table_data, const StorageID & new_table_id)
{
    checkTableCanBeRenamed(new_table_id);
    MergeTreeData::rename(new_path_to_table_data, new_table_id);
    
    if (!is_readonly)
    {
        
        
        try
        {
            auto zookeeper = getZooKeeper();
            zookeeper->set(fs::path(replica_path) / "host", getReplicatedMergeTreeAddress().toString());
        }
        catch (Coordination::Exception & e)
        {
            LOG_WARNING(log, "Cannot update the value of 'host' node (replica address) in ZooKeeper: {}", e.displayText());
        }
    }
    
}
bool StorageReplicatedMergeTree::existsNodeCached(const std::string & path) const