[improve][client-c++] Use an atomic `state_` instead of the lock to improve performance

[coderzc]

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Motivation

Now, Use a lot of locks to ensure the atomicity of state_ in the ConsumerImpl, ProducerImpl, PartitionedConsumerImpl, and MultiTopicsConsumerImpl, we can use atomic state_ instead of the lock to improve performance.

Modifications

Use an atomic state_ instead of the lock to improve performance.

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[shibd]

@coderzc PartitionedConsumerImpl and MultiTopicsConsumerImpl may be also can improve

[coderzc]

@coderzc PartitionedConsumerImpl and MultiTopicsConsumerImpl may be also can improve

Thanks, I have already improved them.

[coderzc]

/pulsarbot run-failure-checks

[mattisonchao]

@BewareMyPower @shibd Could you review it again?

[coderzc]

/pulsarbot run-failure-checks

[coderzc]

@BewareMyPower PTAL

[BewareMyPower]

The correct process on the following code might be a little complicated. I think we can add a TODO here.

      if (state_ != Ready && state_ != Pending) {
          state_ = Closed;

[BewareMyPower]

Just left one final minor comment, LGTM.