Introduce a way to easily check cluster status

[sazzad16]

Expected behavior

There should be a easy to check if the cluster is initialized properly. I.e. if there is a pool initialized for each hash slot.

For example, if we add a isInitialized(), users would at least be able to do

JedisCluster cluster = new JedisCluster(...);
if (!cluster.isInitialized()) {
  ...
}

Actual behavior

Currently it can be done by getClusterNodes(), may be combining with a command, like PING. But we should introduce a easier way.

[sazzad16]

Ref #2275: I don't completely support throwing exception because we don't do that even from Jedis class. Throwing exception from JedisCluster constructor seems contradictory to me.

[github-actions]

This issue is marked stale. It will be closed in 30 days if it is not updated.

[sazzad16]

1. JedisCluster constructors now throws an exception if it cannot connect to any HostAndPort (throw exception if JedisCluster cannot connect to any host-port #2721)
2. JedisCluster now has PING command that accumulates responses from all nodes (OSS Broadcast support #3285)

Closing this issue in favor of these options.