Fix KF Dex authentication bug

[ptitzler]

This PR

• handles Kubeflow [Dex] authentication issues
  • missing credentials
  • partial credentials
  • invalid credentials
• closes Handle Kubeflow authentication/authorization errors #1636

What changes were proposed in this pull request?

• Fix faulty code

• Add log message for problem determination, should authentication fail

   Kubeflow authentication info: {'endpoint': 'http://custard1.fyre.ibm.com:31380', 'endpoint_response_url': 'http://custard1.fyre.ibm.com:31380/dex/auth/local?req=ywzv...cy', 'endpoint_secured': True, 'authservice_session_cookie': None}
  

• Add proper error message

  

How was this pull request tested?

• connect to unsecured KF without credentials in the RTC (expected to succeed)
• connect to unsecured KF with credentials in the RTC (expected to succeed)
• connect to unsecured KF with only user name defined in the RTC (expected to succeed)
• connect to unsecured KF with only password defined in the RTC (expected to succeed)
• connect to secured KF without credentials in the RTC (expected to fail)
• connect to secured KF with invalid credentials in the RTC (expected to fail)
• connect to secured KF with only user name defined in the RTC (expected to fail)
• connect to secured KF with only password defined in the RTC (expected to fail)
• connect to secured KF with valid credentials in the RTC (expected to succeed)

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[kevin-bates]

Thanks @ptitzler - this looks good and I'm approving from a code perspective. I can't test this, but trust you'll be doing that. My only comment was a nit regarding the log level that feels more troubleshooting-related than informational.

[ptitzler]

All tests completed as expected, including informal test of debug output.