Feature: GSSAPI (Kerberos) support

[roma-frolov]

Description

Fixed #1608

Type of change

• New feature (a non-breaking change that adds functionality)

Checklist

• My code adheres to the style guidelines of this project (scripts/lint.sh shows no errors)
• I have conducted a self-review of my own code
• I have made the necessary changes to the documentation
• My changes do not generate any new warnings
• I have added tests to validate the effectiveness of my fix or the functionality of my new feature
• Both new and existing unit tests pass successfully on my local environment by running scripts/test-cov.sh
• I have ensured that static analysis tests are passing by running scripts/static-analysis.sh
• I have included code examples to illustrate the modifications

[roma-frolov]

I want to clarify something: aiokafka with sasl_mechanism == GSSAPI requires the gssapi library (here). This library is optional in aiokafka (here).

What to do here? Add the gssapi library as optional? Are additional checks needed?

[Lancetnik]

Hi! Thank you for the PR - it looks really good. But, if you added docs/docs_src file, can you please include it to the documentation the same way with other ones? Also, we are trying to cover all such examples by test, so can you please add test for it as well (tests/docs/etc directory)?

[Lancetnik]

Why you added this file, but didn't use it anywhere?

[roma-frolov]

I included this file in the documentation, but I already wrote the test earlier, here it is.
Is this enough?

[Lancetnik]

Can u a test for it too? https://github.com/airtai/faststream/blob/main/tests/docs/kafka/test_security.py

[roma-frolov]

done

[kumaranvpl]

@Lancetnik This PR added Kerberos support only for aiokafka broker, not for confluent broker.
I have created a separate issue for it - #1669. I will create a PR for it in few mins.