Enhancement: Added Kafka OIDC + azure.identity independent producer/consumer examples.

[Pilipets]

There were no examples for Kafka OIDC and accessing the Azure event hub without the azure identity library.

This pull request introduces new examples of producer/consumer to address the above issues:

1. OIDC SASL_SSL - get_oidc_config
2. SASL_SSL with custom token refresh callback without azure.identity dependency - get_cb_config

The current PR is a draft one - let me know if you find it useful.
Then I will create README.md, will write code in more OOP-like manner and add more comments for the used concepts.

More context one can gather from the issue I created recently.
Examples are based on the existing code in tutorials for Python-oauth.

CC @hmlam

[Pilipets]

@microsoft-github-policy-service agree

@microsoft-github-policy-service agree

[hmlam]

Just some house-keeping comments

• since it is OIDC sample, we can probably use the folder "oidc" (or OpenIdConnect) as oppose to more_example.
• sample will need to have the default comment header for licenses etc. example can be taken from other samples.

[Pilipets]

@hmlam, sorry for the delay in response.

I didn't want to duplicate the same producer/consumer logic for oidc, opaque folders, so decided to modify the structure of producer/consumer and extend the usage functionality.

1. Added license headers as you requested.
2. Added config_utils.py that provides producer configs for three modes - azure, oidc, opaque.
3. Extended producer, consumer functionality to be able to run those with --mode which is one of above mentioned modes.
4. No need to change README.md because both Python scripts can be used as before. Therefore, backward compatibility is maintained, and newly added functionality is optional.
5. Tested all the changes manually.
6. I preserved all the comments and added new ones for oidc, opaque modes:
   • oidc corresponds to KIP-768 and decoding JWT with the usage of exp claim
   • opaque utilizes expires_in field and network requests without azure.identity dependency