feat(oidc): client secret jwt client auth

[james-d-elliott]

This adds the authentication machinery for the client_secret_jwt Default Client Authentication Strategy.

[authelia]

Artifacts

These changes are published for testing on Buildkite, DockerHub and GitHub Container Registry.

Docker Container

• docker pull authelia/authelia:feat-client-auth-jwt-hs
• docker pull ghcr.io/authelia/authelia:feat-client-auth-jwt-hs

[codecov]

Codecov Report

Merging #5253 (d3ecfd0) into master (9e5c6ec) will decrease coverage by 0.73%.
The diff coverage is 14.18%.

❗ Current head d3ecfd0 differs from pull request most recent head f415b76. Consider uploading reports for the commit f415b76 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5253      +/-   ##
==========================================
- Coverage   67.59%   66.87%   -0.73%     
==========================================
  Files         278      279       +1     
  Lines       21479    21736     +257     
  Branches      438      438              
==========================================
+ Hits        14519    14536      +17     
- Misses       6165     6393     +228     
- Partials      795      807      +12     

Flag	Coverage Δ
backend	67.74% <14.18%> (-0.78%)	⬇️
frontend	56.52% <ø> (-0.18%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
internal/handlers/handler_oidc_userinfo.go	0.00% <0.00%> (ø)
internal/oidc/types.go	89.33% <0.00%> (-2.45%)	⬇️
internal/oidc/client_auth.go	3.79% <3.79%> (ø)
...rnal/configuration/validator/identity_providers.go	97.23% <82.60%> (-0.94%)	⬇️
internal/oidc/client.go	96.53% <100.00%> (+0.02%)	⬆️
internal/oidc/discovery.go	75.60% <100.00%> (+0.14%)	⬆️
internal/oidc/keys.go	67.67% <100.00%> (ø)
internal/oidc/provider.go	94.33% <100.00%> (+0.10%)	⬆️

... and 2 files with indirect coverage changes

[netlify]

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[james-d-elliott]

Approved in #5280