Simplify ClientConnectionManagerImpl

This commit simplifies the concurrency and state machine logic of
ClientConnectionManagerImpl.

First, a simple mutex is defined and used for the management of connections and
client state and races are prevented during state updates.

Second, the possible client states and their transitions are clarified.
On bootstrap, a client starts with the INITIAL state and moves to
the INITIALIZED_ON_CLUSTER state once it makes its first connection to any
member. Then, whenever this client drops all its connections to the current
cluster and connects to a totally new cluster, it moves to
the CONNECTED_TO_CLUSTER state. Then, the client moves back to
the INITIALIZED_ON_CLUSTER state once it propagates its local state to
the new cluster.

Fixes hazelcast#16288

hazelcast/src/main/java/com/hazelcast/client/impl/clientside/HazelcastClientInstanceImpl.java

@@ -394,7 +394,7 @@ public void start() {
             }
             ClientConnectionStrategyConfig connectionStrategyConfig = config.getConnectionStrategyConfig();
             if (!connectionStrategyConfig.isAsyncStart()) {
-                connectionManager.tryOpenConnectionToAllMembers();
+                connectionManager.connectToAllClusterMembers();
                 waitForInitialMembershipEvents();
             }
             loadBalancer.init(getCluster(), config);
@@ -838,7 +838,7 @@ public void onClusterChange() {
 
     public void onClusterRestart() {
         ILogger logger = loggingService.getLogger(HazelcastInstance.class);
-        logger.info("Clearing local state of the client, because of a cluster restart ");
+        logger.info("Clearing local state of the client, because of a cluster restart");
 
         dispose(onClusterChangeDisposables);
         //clear the member list version

hazelcast/src/main/java/com/hazelcast/client/impl/connection/nio/ClientConnection.java

@@ -196,7 +196,7 @@ public void close(String reason, Throwable cause) {
             logger.warning("Exception while closing connection" + e.getMessage());
         }
 
-        connectionManager.onClose(this);
+        connectionManager.onConnectionClose(this);
     }
 
     private void logClose() {