Add oidc refactor commit from ref impl

[vepatel]

Proposed changes

• this PR takes refactor commit: nginxinc/nginx-openid-connect@66c4eaa#diff-56939fdacf34acf014e8b512c3fab0b7bd601411e001469c552a8844c9a8da3a from reference implementation

local build passes both OIDC automation test:

======================================================== 2 passed, 571 deselected, 24 warnings in 299.89s (0:04:59) ========================================================= 

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.34%. Comparing base (f4ed950) to head (eb1b48b).
Report is 4 commits behind head on main.

Additional details and impacted files

@@ Coverage Diff @@ ## main #7762 +/- ## ======================================= Coverage 52.34% 52.34% ======================================= Files 89 89 Lines 21373 21373 ======================================= Hits 11188 11188 Misses 9719 9719 Partials 466 466 

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