Add "sasl_protocol: oauthbearer" which does not add default handlers

[sverrehu]

Description

Using the existing sasl_protocol: oauth will add callback handlers for Confluent-provided classes. This PR adds a similar sasl_protocol: oauthbearer that will not automatically set up any callback handlers.

Fixes #1089

Type of change

• Bug fix (non-breaking change which fixes an issue)
• [x ] New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Molecule test, and test in our local cluster.

Test Configuration:

Checklist:

• [x ] My code follows the style guidelines of this project
• [ x] I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• [ x] I have made corresponding changes to the documentation
• My changes generate no new warnings
• [ x] I have added tests that prove my fix is effective or that my feature works
• Any dependent changes have been merged and published in downstream modules
• Any variable changes have been validated to be backwards compatible

[erikgb]

LGTM, but we could consider a separate PR to catch up the missing re-gen of md-files.

[nsharma-git]

Should we not update this condition to check the property confluent_server_enabled That way probably we don't need to add another mechanism.

[domenicbove]

does there need to be 2 if statements

            if self.normalize_sasl_protocol(listeners_dict[listener].get('sasl_protocol', default_sasl_protocol)) == 'OAUTHBEARER':
                if listeners_dict[listener].get('sasl_protocol', default_sasl_protocol).upper() == 'OAUTH':

[cla-assistant]

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