Add reduce method to KafkaError and change tp_name

[OneRaynyDay]

According to CPython documentation: https://docs.python.org/3/c-api/typeobj.html#c.PyTypeObject.tp_name

For example, a type named T defined in module M in subpackage Q in package P should have the tp_name initializer "P.Q.M.T".

Here, the module we're talking about is cimpl, and the package is confluent_kafka, so therefore it should be confluent_kafka.cimpl.KafkaError and such for the rest of the classes defined.

Also, I add reduce for KafkaError so we can properly pickle it:

>>> import confluent_kafka >>> import pickle >>> err = confluent_kafka.cimpl.KafkaError(1) >>> err.__reduce__() (<class 'confluent_kafka.cimpl.KafkaError'>, (1, 'Broker: Offset out of range', 0, 0, 0)) >>> pickle.loads(pickle.dumps(err)) KafkaError{code=OFFSET_OUT_OF_RANGE,val=1,str="Broker: Offset out of range"} >>> pickle.loads(pickle.dumps(err)) == err True 

[OneRaynyDay]

Also happy to sign a CLA if necessary.

[joaoe]

According to CPython documentation: https://docs.python.org/3/c-api/typeobj.html#c.PyTypeObject.tp_name

Nice catch. I think that affects all classes implemented in cimpl.

[joaoe]

I also added another PR which also includes support for "reducing" Message objects, which end up benefiting from this pull request, if the Message has error set.

[cla-assistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}