Support for passing basic auth credentials from Python client

[kesavkolla]

If broker is setup with BasicAuth (AuthenticationProviderBasic) currently Python client doesn't have an ability to pass the credentials. Please add support in Python for sending basic auth credentials while connecting to topic.

[sijie]

I think this is a documentation issue to documentation how to pass basic authentication credentials from Python client.

[codelipenghui]

@tuteng Could you help check if the feature is supported?