Language negotiation fixes for Skosmos 3

[osma]

Reasons for creating this PR

Fixes and unit tests for language negotiation were applied to the master branch in PR #1457. This PR applies the same fixes to the skosmos-3 branch. The commits have been cherry-picked and adapted to current Skosmos 3 PHP code style.

Link to relevant issue(s), if any

• Closes Skosmos UI loads in Arabic #1453 (for Skosmos 3)

Description of the changes in this PR

(copied from PR #1457)

• Upgrade willdurand/negotiation from 3.0.* to 3.1.* because only 3.1 is compatible with PHP 8.1
• Add handling of cookie values to the Request class
• Make WebController.guessLanguage use the Request class to access cookies and HTTP header values
• Implement unit tests for WebController.guessLanguage
• Fix the language value passed to in_array (from PR UI language negotiation fix #1455)
• Fix the language tags in skosmos:languages settings in the sample configs for Docker (from PR UI language negotiation fix #1455)

Known problems or uncertainties in this PR

n/a

Checklist

• phpUnit tests pass locally with my changes
• I have added tests that show that the new code works, or tests are not relevant for this PR (e.g. only HTML/CSS changes)
• The PR doesn't reduce accessibility of the front-end code (e.g. tab focus, scaling to different resolutions, use of .sr-only class, color contrast)
• The PR doesn't introduce unintended code changes (e.g. empty lines or useless reindentation)

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

No Coverage information
0.0% Duplication

[codecov]

Codecov Report

Patch coverage: 93.33% and project coverage change: +0.49 🎉

Comparison is base (a62b3f2) 69.50% compared to head (6929962) 70.00%.

Additional details and impacted files

@@               Coverage Diff               @@
##             skosmos-3    #1458      +/-   ##
===============================================
+ Coverage        69.50%   70.00%   +0.49%     
- Complexity        1629     1634       +5     
===============================================
  Files               32       32              
  Lines             4280     4290      +10     
===============================================
+ Hits              2975     3003      +28     
+ Misses            1305     1287      -18     

Impacted Files	Coverage Δ
src/model/Request.php	77.22% <88.88%> (+7.66%)	⬆️
src/controller/WebController.php	19.87% <100.00%> (+4.43%)	⬆️

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