feat(oidc): support per-issuer CA

[matheuscscp]

Closes: #3757

[codecov]

Codecov Report

❌ Patch coverage is 87.50000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.60%. Comparing base (b905528) to head (380c43c).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/api/bearer_oidc.go	87.50%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3760      +/-   ##
==========================================
- Coverage   91.61%   91.60%   -0.01%     
==========================================
  Files         189      189              
  Lines       26926    26930       +4     
==========================================
+ Hits        24668    24670       +2     
- Misses       1459     1460       +1     
- Partials      799      800       +1     

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[matheuscscp]

Codecov Report

❌ Patch coverage is 86.95652% with 3 lines in your changes missing coverage. Please review. ✅ Project coverage is 91.60%. Comparing base (b905528) to head (38bbab6).

Files with missing lines Patch % Lines
pkg/api/bearer_oidc.go 86.95% 1 Missing and 2 partials ⚠️
Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3760      +/-   ##
==========================================
- Coverage   91.61%   91.60%   -0.01%     
==========================================
  Files         189      189              
  Lines       26926    26930       +4     
==========================================
+ Hits        24668    24670       +2     
- Misses       1459     1460       +1     
- Partials      799      800       +1     

☔ View full report in Codecov by Sentry. 📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

The uncovered lines in question are:

+ 		defaultTransport, ok := http.DefaultTransport.(*http.Transport)
+ 		if !ok {
+ 			return nil, fmt.Errorf("%w: failed to get default HTTP transport", zerr.ErrBadConfig)
+ 		}

and

+ 	if hc := o.httpClient; hc != nil {
  		ctx = oidc.ClientContext(ctx, hc)
  	}

The first one cannot be covered since http.DefaultTransport is always *http.Transport, and the second one is covered in the e2e nightly tests.