Add trace and span_id to logging async API

[brunoais]

Follow up to #5885 and #5878. Add function parameters on the logging async API to allow API logging with trace and span_id in a non-blocking way.

[brunoais]

Do I need to add any tests for these changes? If so, may someone please guide me to where such files are?
In order to use stackdriver effectively, I really need this feature.

[brunoais]

       for item in items:
          if item is _WORKER_TERMINATOR:
               quit_ = True
               # Continue processing items, don't break, try to process
               # all items we got back before quitting.
           else:
              batch.log_struct(**item)

E TypeError: log_struct() got an unexpected keyword argument 'trace'

but trace is there (same for span_id) :
https://github.com/GoogleCloudPlatform/google-cloud-python/blob/master/logging/google/cloud/logging/logger.py#L475

Am I seeing things wrong?

[brunoais]

@tseaver please re-review.
Any clue about when the next version comes out? I don't intent to speed up anything, I just want to organize ourselves to use the additions asaco (As Soon As Comes Out).

[tseaver]

@brunoais I'm pretty sure we have a new feature release scheduled for the first week in October. We could make another before then (without that pending feature) if @snehashah16 wants us to.

[brunoais]

OK! Thank you!

[tseaver]

@brunoais Oops, I crossed my wires in that response: @snehashah16 is responsible for spanner, not logging. I think @liyanhui1228 is the logging person.

[tseaver]

@brunoais I just added #5924 to track the release of a new google-cloud-logging version.

[brunoais]

Got it. Thanks for both m8!