Allow flink onprem commands to work with MDS auth

[vsantwana]

What we've tested:

• Unit tests added for all the commands.
• Manual testing for environment and application related commands.

This PR is ready to be merged after the review.

Release Notes

New Features

• Allow on-premises Flink commands to work with MDS authentication.

Checklist

• [*] I have successfully built and used a custom CLI binary, without linter issues from this PR.
• [*] I have clearly specified in the What section below whether this PR applies to Confluent Cloud, Confluent Platform, or both.
• I have verified this PR in Confluent Cloud pre-prod or production environment, if applicable.
• I have verified this PR in Confluent Platform on-premises environment, if applicable.
• I have attached manual CLI verification results or screenshots in the Test & Review section below.
• [*] I have added appropriate CLI integration or unit tests for any new or updated commands and functionality.
• [*] I confirm that this PR introduces no breaking changes or backward compatibility issues.
• [*] I have indicated the potential customer impact if something goes wrong in the Blast Radius section below.
• I have put checkmarks below confirming that the feature associated with this PR is enabled in:
  • Confluent Cloud prod
  • Confluent Cloud stag
  • [*] Confluent Platform
  • Check this box if the feature is enabled for certain organizations only

What

What: Changes the command creation bit for the Flink command, to deal with the case when the user is authenticated with MDS.

Why: Currently the flink onprem commands are able to run with mTLS (only), this adds the capability to run them with MDS too.

Applies to confluent platform.

Blast Radius

Will affect on-premises flink command usage.

References

Test & Review

[confluent-cla-assistant]

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