Log flow commands before sending to broker

Just we like how the [received command is logged ](https://github.com/apache/pulsar-client-go/blob/master/pulsar/internal/connection_reader.go#L59)on receiving from broker, It will be helpful to debug issues on client side if [sent command is also logged here](https://github.com/apache/pulsar-client-go/blob/master/pulsar/internal/connection.go#L500) while sending it to broker something like below.

```go
// log the command before sending to broker, it will be helpful for debugging in case of issues
c.log.Debugf("Writing command: %v", cmd)
```

Read pulsar/internal/connection.go around line 500 and compare it with the received-command logging in pulsar/internal/connection_reader.go around line 59. Confirm where commands are sent to the broker and add logging immediately before that send. Done means outgoing commands are logged in the same debugging flow as received commands without changing command delivery.

Written by the indexing model from the issue text.