SNOW-1739611 add automated tests for okta, oauth and keypair

[sfc-gh-akolodziejczyk]

Description

SNOW-1739611

1. Extracted reusable code from external browser tests to authTestsBaseClass.js
2. Added tests for Oauth and Okta

Checklist

• Format code according to the existing code style (run npm run lint:check -- CHANGED_FILES and fix problems in changed code)
• Create tests which fail without the change (if possible)
• Make all tests (unit and integration) pass (npm run test:unit and npm run test:integration)
• Extend the README / documentation and ensure is properly displayed (if necessary)
• Provide JIRA issue id (if possible) or GitHub issue id in commit message

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.95%. Comparing base (e6f30aa) to head (4ca6b2b).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #976   +/-   ##
=======================================
  Coverage   88.95%   88.95%           
=======================================
  Files          69       69           
  Lines        6754     6754           
=======================================
  Hits         6008     6008           
  Misses        746      746           

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