**Use case**

Currently, `system.replicas` table has `total_replicas` and `active_replicas` columns which are useful to check/alert when some replicas are down. One problem, these columns are numbers. They tell when there is a problem, but you need to further check ZooKeeper or query all the nodes to detect what exact replicas (hosts) are down/inactive/have problems.

**Describe the solution you'd like**

Add a replicas column maybe as a map which would contain the replica name, and it's status. Or, add 2 array columns with `replica_names` and `active_replica_names`

**Alternative**

Something along the line

```sql
select path, value from system.zookeeper where path IN (
    select concat(path, '/', name) from system.zookeeper where path in (select concat(zookeeper_path, '/replicas') from system.replicas)
)
and name = 'is_active'
```
{
    if (!zookeeper_path.empty() && zookeeper_path.back() == '/')
        zookeeper_path.resize(zookeeper_path.size() - 1);
    
    if (!zookeeper_path.empty() && zookeeper_path.front() != '/')
        zookeeper_path = "/" + zookeeper_path;
    return zookeeper_path;
}
static String extractZooKeeperName(const String & path)
{
    if (path.empty())
        throw Exception("ZooKeeper path should not be empty", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
    auto pos = path.find(':');
    if (pos != String::npos)
    {
        auto zookeeper_name = path.substr(0, pos);
        if (zookeeper_name.empty())
            throw Exception("Zookeeper path should start with '/' or '<auxiliary_zookeeper_name>:/'", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
        return zookeeper_name;
    }
    static constexpr auto default_zookeeper_name = "default";
    return default_zookeeper_name;
}
static String extractZooKeeperPath(const String & path)