SNOW-933240: Use custom httpclient for Okta auth

[sfc-gh-pbulawa]

Description

Use the SF custom httpclient for the communication with Okta provider.

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

Merging #686 (51f6c6c) into master (97081e3) will decrease coverage by 0.08%.
The diff coverage is 77.41%.

@@            Coverage Diff             @@
##           master     #686      +/-   ##
==========================================
- Coverage   87.80%   87.72%   -0.08%     
==========================================
  Files          61       61              
  Lines        5725     5745      +20     
==========================================
+ Hits         5027     5040      +13     
- Misses        698      705       +7     

Files	Coverage Δ
lib/connection/connection.js	86.85% <100.00%> (+0.07%)	⬆️
lib/authentication/authentication.js	67.85% <85.71%> (+6.98%)	⬆️
lib/authentication/auth_okta.js	87.27% <85.71%> (-2.73%)	⬇️
lib/http/base.js	85.22% <55.55%> (-3.39%)	⬇️

... and 1 file with indirect coverage changes

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[sfc-gh-pmotacki]

LGTM