feat(oidc): per-client pkce enforcement policy

[james-d-elliott]

This implements a per-client PKCE enforcement policy with the ability to enforce that it's used, and the specific challenge mode.

[authelia]

Artifacts

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

Docker Container

• docker pull authelia/authelia:feat-oidc-per-client-pkce
• docker pull ghcr.io/authelia/authelia:feat-oidc-per-client-pkce

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[codecov]

Codecov Report

Merging #4692 (7b38f84) into master (1e86cb9) will increase coverage by 0.02%.
The diff coverage is 75.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4692      +/-   ##
==========================================
+ Coverage   67.41%   67.43%   +0.02%     
==========================================
  Files         266      266              
  Lines       19333    19367      +34     
  Branches      431      431              
==========================================
+ Hits        13034    13061      +27     
- Misses       5543     5550       +7     
  Partials      756      756              

Flag	Coverage Δ
backend	67.84% <75.00%> (+0.01%)	⬆️
frontend	62.65% <ø> (+0.04%)	⬆️

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

Impacted Files	Coverage Δ
internal/handlers/handler_oidc_authorization.go	42.52% <0.00%> (-4.91%)	⬇️
internal/oidc/types.go	91.78% <ø> (ø)
...rnal/configuration/validator/identity_providers.go	98.77% <100.00%> (+0.02%)	⬆️
internal/oidc/client.go	100.00% <100.00%> (ø)
internal/ntp/util.go	88.46% <0.00%> (+3.84%)	⬆️
web/src/services/SignOut.ts	100.00% <0.00%> (+14.28%)	⬆️