feat: implement OIDC Authentication

[bakito]

This PR implements optional OIDC authentication for shiori.

OIDC can be configured via Env Variables.

For testing purposes a simple node oidc-test server is provided.

[codecov]

Codecov Report

❌ Patch coverage is 91.89189% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 52.74%. Comparing base (585ea34) to head (4fbb589).

Files with missing lines	Patch %	Lines
internal/http/handlers/api/v1/oidc.go	88.78%	9 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1184      +/-   ##
==========================================
+ Coverage   50.19%   52.74%   +2.54%     
==========================================
  Files          75       76       +1     
  Lines        7532     5948    -1584     
==========================================
- Hits         3781     3137     -644     
+ Misses       3414     2471     -943     
- Partials      337      340       +3     

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