CORS wildcard origin and allow credentials

[aldas]

Add middleware.CORSConfig.UnsafeWildcardOriginWithAllowCredentials to make UNSAFE usages of wildcard origin + allow cretentials less likely.

See: #2400

[codecov]

Codecov Report

Base: 92.80% // Head: 92.80% // No change to project coverage 👍

Coverage data is based on head (581ebc3) compared to base (b888a30).
Patch coverage: 60.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2405   +/-   ##
=======================================
  Coverage   92.80%   92.80%           
=======================================
  Files          38       38           
  Lines        4506     4506           
=======================================
  Hits         4182     4182           
  Misses        236      236           
  Partials       88       88           

Impacted Files	Coverage Δ
middleware/csrf.go	89.42% <33.33%> (ø)
middleware/jwt.go	92.98% <33.33%> (ø)
middleware/cors.go	92.85% <100.00%> (ø)
middleware/key_auth.go	93.42% <100.00%> (ø)

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[aldas]

@lammel ping

[lammel]

LGTM.
Nothing to add.