SASL_SSL OAUTHBEARER support for high level consumer

[Rastusik]

This PR addresses #580 .

I also extracted the main logic into a separate oauthbearer.c file, so it's not copy pasted into 2 places.

I will be happy for any help or support or feedback, since this is the first time I'm working on a PHP extension.

EDIT: I also needed to implement the poll() method to KafkaConsumer because I had problems with calling getMetadata() and getCommittedOffsets().

[Rastusik]

hey @arnaud-lb Is there any way to make the pipeline run? Is there anything else that needs to be done to move forward with this PR? No pressure, I just am trying to figure out how things work here.

[oaattia]

Waiting for the one to be merged soon.

[Rastusik]

@oaattia Is there anything I can do to speed up the PR process?

[oaattia]

I don't know, I just need this feature :)
may be @arnaud-lb can help with that