**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'
```
for (const String& part_name : active_parts_names)
            attachPartition(std::make_shared<ASTLiteral>(part_name), metadata_snapshot, true, getContext());
    LOG_INFO(log, "Attached all partitions, starting table");
    startup();
    are_restoring_replica.store(false);
}
void StorageReplicatedMergeTree::dropPartNoWaitNoThrow(const String & part_name)
{
    assertNotReadonly();
    if (!is_leader)
        throw Exception("DROP PART cannot be done on this replica because it is not a leader", ErrorCodes::NOT_A_LEADER);
    zkutil::ZooKeeperPtr zookeeper = getZooKeeper();
    LogEntry entry;
    dropPartImpl(zookeeper, part_name, entry,  false,  false);
}
void StorageReplicatedMergeTree::dropPart(const String & part_name, bool detach, ContextPtr query_context)
{
    assertNotReadonly();
    if (!is_leader)
        throw Exception("DROP PART cannot be done on this replica because it is not a leader", ErrorCodes::NOT_A_LEADER);
    zkutil::ZooKeeperPtr zookeeper = getZooKeeper();
    LogEntry entry;
    dropPartImpl(zookeeper, part_name, entry, detach,  true);
    
    if (query_context->getSettingsRef().replication_alter_partitions_sync == 1)
        waitForReplicaToProcessLogEntry(replica_name, entry);
    else if (query_context->getSettingsRef().replication_alter_partitions_sync == 2)
        waitForAllReplicasToProcessLogEntry(entry);
}
void StorageReplicatedMergeTree::dropPartition(const ASTPtr & partition, bool detach, ContextPtr query_context)