Close the channel before sending data if the consumer has been shutdown.

### # The Question
For the consumer, the closing and writing of msgCh are in two coroutines. Even though the chan of `closeChan` is added, since `case` clauses will be randomly executed for the `select` statement, it is still possible Write data to a closed channel
```go
if !pq.order {
select {
case <-pq.closeChan:
return
case pq.msgCh <- messages:
}
}
```
https://github.com/apache/rocketmq-client-go/blob/master/consumer/process_queue.go#LL124C1-L130C3

### # How fo fix?
We'd better close the channel in the goroutine that pullMessage to avoid closing and writing at the same time.