feat: getting OIDC client ID from secret

[zhaohuabing]

This PRs adds support for using Secret as a source of the OIDC client ID.
Implement: #5153
Release note: yes

[codecov]

Codecov Report

Attention: Patch coverage is 26.31579% with 28 lines in your changes missing coverage. Please review.

Project coverage is 71.05%. Comparing base (10baf87) to head (af304e3).

Files with missing lines	Patch %	Lines
internal/provider/kubernetes/controller.go	0.00%	16 Missing ⚠️
internal/gatewayapi/securitypolicy.go	52.63%	7 Missing and 2 partials ⚠️
internal/provider/kubernetes/indexers.go	0.00%	2 Missing and 1 partial ⚠️

❌ Your patch check has failed because the patch coverage (26.31%) is below the target coverage (60.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6532      +/-   ##
==========================================
- Coverage   71.09%   71.05%   -0.04%     
==========================================
  Files         220      220              
  Lines       37970    38006      +36     
==========================================
+ Hits        26993    27005      +12     
- Misses       9401     9423      +22     
- Partials     1576     1578       +2     

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