ClientOptions should get a Logger field to allow injecting of an external Logger

It is available in the old cgo based go client library:

```
// Provide a custom logger implementation where all Pulsar library info/warn/error messages will be routed
// By default, log messages will be printed on standard output. By passing a logger function, application
// can determine how to print logs. This function will be called each time the Pulsar client library wants
// to write any logs.
Logger func(level log.LoggerLevel, file string, line int, message string)
```

Start at the Go client's ClientOptions entry point and trace how library log messages are currently emitted. Compare the requested Logger signature with the old cgo client behavior; done means callers can inject an external logger that receives Pulsar library messages while the default logging behavior remains available.

Written by the indexing model from the issue text.